wrote this diff while debugging the date formatting issue just fixed,
when i realized that we could save a few lines by using strftime().
since I already wrote this diff for repo_write.c, here's also the rest
of the get_datestr() copies converted.  (well, except got-notify-email)

the output is exactly the same as before.

diff /home/op/w/got
commit - 166674b8808a9a16a3cff59d166410cd37833014
path + /home/op/w/got
blob - 38191d6109e5f5caf08654969f4f3af3d9fb2c70
file + cvg/cvg.c
--- cvg/cvg.c
+++ cvg/cvg.c
@@ -3345,21 +3345,16 @@ done:
 }
 
 static char *
-get_datestr(time_t *time, char *datebuf)
+get_datestr(time_t *time, char *datebuf, size_t len)
 {
 	struct tm mytm, *tm;
-	char *p, *s;
 
 	tm = gmtime_r(time, &mytm);
 	if (tm == NULL)
 		return NULL;
-	s = asctime_r(tm, datebuf);
-	if (s == NULL)
+	if (strftime(datebuf, len, "%a %b %e %X %Y UTC", tm) == 0)
 		return NULL;
-	p = strchr(s, '\n');
-	if (p)
-		*p = '\0';
-	return s;
+	return datebuf;
 }
 
 static const struct got_error *
@@ -3644,7 +3639,7 @@ print_commit(struct got_commit_object *commit, struct 
 	const struct got_error *err = NULL;
 	FILE *f = NULL;
 	char *id_str, *datestr, *logmsg0, *logmsg, *line;
-	char datebuf[26];
+	char datebuf[30];
 	time_t committer_time;
 	const char *author, *committer;
 	char *refs_str = NULL;
@@ -3681,9 +3676,9 @@ print_commit(struct got_commit_object *commit, struct 
 	if (strcmp(author, committer) != 0)
 		printf("via: %s\n", committer);
 	committer_time = got_object_commit_get_committer_time(commit);
-	datestr = get_datestr(&committer_time, datebuf);
+	datestr = get_datestr(&committer_time, datebuf, sizeof(datebuf));
 	if (datestr)
-		printf("date: %s UTC\n", datestr);
+		printf("date: %s\n", datestr);
 	if (got_object_commit_get_nparents(commit) > 1) {
 		const struct got_object_id_queue *parent_ids;
 		struct got_object_qid *qid;
@@ -5901,7 +5896,7 @@ list_tags(struct got_repository *repo, const char *tag
 	TAILQ_FOREACH(re, &refs, entry) {
 		const char *refname;
 		char *refstr, *tagmsg0, *tagmsg, *line, *id_str, *datestr;
-		char datebuf[26];
+		char datebuf[30];
 		const char *tagger, *ssh_sig = NULL;
 		char *sig_msg = NULL;
 		time_t tagger_time;
@@ -5968,9 +5963,9 @@ list_tags(struct got_repository *repo, const char *tag
 		printf("%stag %s %s\n", GOT_COMMIT_SEP_STR, refname, refstr);
 		free(refstr);
 		printf("from: %s\n", tagger);
-		datestr = get_datestr(&tagger_time, datebuf);
+		datestr = get_datestr(&tagger_time, datebuf, sizeof(datebuf));
 		if (datestr)
-			printf("date: %s UTC\n", datestr);
+			printf("date: %s\n", datestr);
 		if (commit)
 			printf("object: %s %s\n", GOT_OBJ_LABEL_COMMIT, id_str);
 		else {
blob - 4486b08390756e709d18c25cbfc370d75101ecc2
file + got/got.c
--- got/got.c
+++ got/got.c
@@ -4036,21 +4036,16 @@ done:
 }
 
 static char *
-get_datestr(time_t *time, char *datebuf)
+get_datestr(time_t *time, char *datebuf, size_t len)
 {
 	struct tm mytm, *tm;
-	char *p, *s;
 
 	tm = gmtime_r(time, &mytm);
 	if (tm == NULL)
 		return NULL;
-	s = asctime_r(tm, datebuf);
-	if (s == NULL)
+	if (strftime(datebuf, len, "%a %b %e %X %Y UTC", tm) == 0)
 		return NULL;
-	p = strchr(s, '\n');
-	if (p)
-		*p = '\0';
-	return s;
+	return datebuf;
 }
 
 static const struct got_error *
@@ -4335,7 +4330,7 @@ print_commit(struct got_commit_object *commit, struct 
 	const struct got_error *err = NULL;
 	FILE *f = NULL;
 	char *id_str, *datestr, *logmsg0, *logmsg, *line;
-	char datebuf[26];
+	char datebuf[30];
 	time_t committer_time;
 	const char *author, *committer;
 	char *refs_str = NULL;
@@ -4372,9 +4367,9 @@ print_commit(struct got_commit_object *commit, struct 
 	if (strcmp(author, committer) != 0)
 		printf("via: %s\n", committer);
 	committer_time = got_object_commit_get_committer_time(commit);
-	datestr = get_datestr(&committer_time, datebuf);
+	datestr = get_datestr(&committer_time, datebuf, sizeof(datebuf));
 	if (datestr)
-		printf("date: %s UTC\n", datestr);
+		printf("date: %s\n", datestr);
 	if (got_object_commit_get_nparents(commit) > 1) {
 		const struct got_object_id_queue *parent_ids;
 		struct got_object_qid *qid;
@@ -7460,7 +7455,7 @@ list_tags(struct got_repository *repo, const char *tag
 	TAILQ_FOREACH(re, &refs, entry) {
 		const char *refname;
 		char *refstr, *tagmsg0, *tagmsg, *line, *id_str, *datestr;
-		char datebuf[26];
+		char datebuf[30];
 		const char *tagger, *ssh_sig = NULL;
 		char *sig_msg = NULL;
 		time_t tagger_time;
@@ -7527,9 +7522,9 @@ list_tags(struct got_repository *repo, const char *tag
 		printf("%stag %s %s\n", GOT_COMMIT_SEP_STR, refname, refstr);
 		free(refstr);
 		printf("from: %s\n", tagger);
-		datestr = get_datestr(&tagger_time, datebuf);
+		datestr = get_datestr(&tagger_time, datebuf, sizeof(datebuf));
 		if (datestr)
-			printf("date: %s UTC\n", datestr);
+			printf("date: %s\n", datestr);
 		if (commit)
 			printf("object: %s %s\n", GOT_OBJ_LABEL_COMMIT, id_str);
 		else {
blob - 35a2c6bb85273ba11c1a12f58fd24d93c3e3843c
file + gotd/libexec/got-notify-email/got-notify-email.c
--- gotd/libexec/got-notify-email/got-notify-email.c
+++ gotd/libexec/got-notify-email/got-notify-email.c
@@ -193,21 +193,16 @@ send_smtp_msg(int s, const char *fmt, ...)
 }
 
 static char *
-get_datestr(time_t *time, char *datebuf)
+get_datestr(time_t *time, char *datebuf, size_t len)
 {
 	struct tm mytm, *tm;
-	char *p, *s;
 
 	tm = gmtime_r(time, &mytm);
 	if (tm == NULL)
 		return NULL;
-	s = asctime_r(tm, datebuf);
-	if (s == NULL)
+	if (strftime(datebuf, len, "%a %b %e %X %Y +0000 (UTC)", tm) == 0)
 		return NULL;
-	p = strchr(s, '\n');
-	if (p)
-		*p = '\0';
-	return s;
+	return datebuf;
 }
 
 static void
@@ -220,11 +215,11 @@ send_email(int s, const char *myfromaddr, const char *
 	size_t linesize = 0;
 	ssize_t linelen;
 	time_t now;
-	char datebuf[26];
+	char datebuf[38];
 	char *datestr;
 
 	now = time(NULL);
-	datestr = get_datestr(&now, datebuf);
+	datestr = get_datestr(&now, datebuf, sizeof(datebuf));
 
 	if (read_smtp_code(s, "220"))
 		errx(1, "unexpected SMTP greeting received");
@@ -257,7 +252,7 @@ send_email(int s, const char *myfromaddr, const char *
 		if (send_smtp_msg(s, "Reply-To: %s\r\n", replytoaddr))
 			errx(1, "could not send Reply-To header");
 	}
-	if (send_smtp_msg(s, "Date: %s +0000 (UTC)\r\n", datestr))
+	if (send_smtp_msg(s, "Date: %s\r\n", datestr))
 		errx(1, "could not send Date header");
 
 	if (send_smtp_msg(s, "Subject: %s\r\n", subject))
blob - 787504ad4f6f0817c648d3f24b5d75d65da66010
file + gotd/repo_write.c
--- gotd/repo_write.c
+++ gotd/repo_write.c
@@ -1630,21 +1630,16 @@ receive_pack_idx(struct imsg *imsg, struct gotd_imsgev
 }
 
 static char *
-get_datestr(time_t *time, char *datebuf)
+get_datestr(time_t *time, char *datebuf, size_t len)
 {
 	struct tm mytm, *tm;
-	char *p, *s;
 
 	tm = gmtime_r(time, &mytm);
 	if (tm == NULL)
 		return NULL;
-	s = asctime_r(tm, datebuf);
-	if (s == NULL)
+	if (strftime(datebuf, len, "%a %b %e %X %Y UTC", tm) == 0)
 		return NULL;
-	p = strchr(s, '\n');
-	if (p)
-		*p = '\0';
-	return s;
+	return datebuf;
 }
 
 static const struct got_error *
@@ -1776,7 +1771,7 @@ print_commit(struct got_commit_object *commit, struct 
 {
 	const struct got_error *err = NULL;
 	char *id_str, *datestr, *logmsg0, *logmsg, *line;
-	char datebuf[26];
+	char datebuf[30];
 	time_t committer_time;
 	const char *author, *committer;
 
@@ -1793,9 +1788,9 @@ print_commit(struct got_commit_object *commit, struct 
 	if (strcmp(author, committer) != 0)
 		dprintf(fd, "via: %s\n", committer);
 	committer_time = got_object_commit_get_committer_time(commit);
-	datestr = get_datestr(&committer_time, datebuf);
+	datestr = get_datestr(&committer_time, datebuf, sizeof(datebuf));
 	if (datestr)
-		dprintf(fd, "date: %s UTC\n", datestr);
+		dprintf(fd, "date: %s\n", datestr);
 	if (got_object_commit_get_nparents(commit) > 1) {
 		const struct got_object_id_queue *parent_ids;
 		struct got_object_qid *qid;
@@ -2005,7 +2000,7 @@ print_tag(struct got_object_id *id,
 	struct got_tag_object *tag = NULL;
 	const char *tagger = NULL;
 	char *id_str = NULL, *tagmsg0 = NULL, *tagmsg, *line, *datestr;
-	char datebuf[26];
+	char datebuf[30];
 	time_t tagger_time;
 
 	err = got_object_open_as_tag(&tag, repo, id);
@@ -2021,9 +2016,9 @@ print_tag(struct got_object_id *id,
 
 	dprintf(fd, "tag %s\n", refname);
 	dprintf(fd, "from: %s\n", tagger);
-	datestr = get_datestr(&tagger_time, datebuf);
+	datestr = get_datestr(&tagger_time, datebuf, sizeof(datebuf));
 	if (datestr)
-		dprintf(fd, "date: %s UTC\n", datestr);
+		dprintf(fd, "date: %s\n", datestr);
 
 	switch (got_object_tag_get_object_type(tag)) {
 	case GOT_OBJ_TYPE_BLOB:
blob - d6f39ddd87489a5be6dceeaae758836ca25385f3
file + gotwebd/pages.tmpl
--- gotwebd/pages.tmpl
+++ gotwebd/pages.tmpl
@@ -89,14 +89,15 @@ nextsep(char *s, char **t)
 	if (strftime(rfc3339, sizeof(rfc3339), "%FT%TZ", &tm) == 0)
 		return -1;
 
-	if (fmt != TM_DIFF && asctime_r(&tm, datebuf) == NULL)
+	if (fmt != TM_DIFF &&
+	    strftime(datebuf, sizeof(datebuf), "%a %b %e %X %Y UTC" &tm) == 0)
 		return -1;
 !}
 <time datetime="{{ rfc3339 }}">
   {{ if fmt == TM_DIFF }}
     {{ render gotweb_render_age(tp, t) }}
   {{ else }}
-    {{ datebuf }} {{ " UTC" }}
+    {{ datebuf }}
   {{ end }}
 </time>
 {{ end }}
blob - 49be7dc0e431407602c4dba0ac7030028d5a567e
file + tog/tog.c
--- tog/tog.c
+++ tog/tog.c
@@ -5032,21 +5032,16 @@ draw_file(struct tog_view *view, const char *header)
 }
 
 static char *
-get_datestr(time_t *time, char *datebuf)
+get_datestr(time_t *time, char *datebuf, size_t len)
 {
 	struct tm mytm, *tm;
-	char *p, *s;
 
 	tm = gmtime_r(time, &mytm);
 	if (tm == NULL)
 		return NULL;
-	s = asctime_r(tm, datebuf);
-	if (s == NULL)
+	if (strftime(datebuf, len, "%a %b %e %X %Y UTC", tm) == 0)
 		return NULL;
-	p = strchr(s, '\n');
-	if (p)
-		*p = '\0';
-	return s;
+	return datebuf;
 }
 
 static const struct got_error *
@@ -5128,7 +5123,7 @@ write_commit_info(struct got_diff_line **lines, size_t
     struct got_diffstat_cb_arg *dsa, FILE *outfile)
 {
 	const struct got_error *err = NULL;
-	char datebuf[26], *datestr;
+	char datebuf[30], *datestr;
 	struct got_commit_object *commit;
 	char *id_str = NULL, *logmsg = NULL, *s = NULL, *line;
 	time_t committer_time;
@@ -5193,9 +5188,9 @@ write_commit_info(struct got_diff_line **lines, size_t
 			goto done;
 	}
 	committer_time = got_object_commit_get_committer_time(commit);
-	datestr = get_datestr(&committer_time, datebuf);
+	datestr = get_datestr(&committer_time, datebuf, sizeof(datebuf));
 	if (datestr) {
-		n = fprintf(outfile, "date: %s UTC\n", datestr);
+		n = fprintf(outfile, "date: %s\n", datestr);
 		if (n < 0) {
 			err = got_error_from_errno("fprintf");
 			goto done;