It does not seem useful to allow rebase of references outside the
"refs/heads/" namespace. Just like 'got commit' refuses to change
references outside of this namespace, 'got rebase' should refuse
to change them.

ok?

diff e72b098390333cd6d10b39518001fba7ba6a1790 6d141363b49d169a3918f862093595702c08d8a1
commit - e72b098390333cd6d10b39518001fba7ba6a1790
commit + 6d141363b49d169a3918f862093595702c08d8a1
blob - bdf06b70325f2720ec4a7f3bcdc35c740b1052f2
blob + 6cf8ccdbc08a98cb14efa193fceb1eb92fd05f97
--- got/got.1
+++ got/got.1
@@ -2144,6 +2144,11 @@ when the rebase operation continues.
 .Pp
 .Cm got rebase
 will refuse to run if certain preconditions are not met.
+If the
+.Ar branch
+is not in the
+.Dq refs/heads/
+reference namespace, the branch may not be rebased.
 If the work tree is not yet fully updated to the tip commit of its
 branch, then the work tree must first be updated with
 .Cm got update .
blob - 64ef5fc0ef4b1bd3dce557f8ecb20c5f2946dee6
blob + e8369725fe5afccaf92cac20559a3594304240bd
--- got/got.c
+++ got/got.c
@@ -10228,6 +10228,12 @@ cmd_rebase(int argc, char *argv[])
 		error = got_ref_open(&branch, repo, argv[0], 0);
 		if (error != NULL)
 			goto done;
+		if (strncmp(got_ref_get_name(branch), "refs/heads/", 11) != 0) {
+			error = got_error_msg(GOT_ERR_COMMIT_BRANCH,
+			    "will not rebase a branch which lives outside "
+			    "the \"refs/heads/\" reference namespace");
+			goto done;
+		}
 	}
 
 	error = got_ref_resolve(&branch_head_commit_id, repo, branch);
blob - b2315194a6347d2b00b98f019861b2b6776d08ef
blob + 59b9d0cacb742bc1bd8bb4c444a37d5f22de820a
--- regress/cmdline/rebase.sh
+++ regress/cmdline/rebase.sh
@@ -1656,6 +1656,33 @@ test_rebase_no_author_info() {
 	test_done "$testroot" "$ret"
 }
 
+test_rebase_nonbranch() {
+	local testroot=`test_init rebase_nonbranch`
+
+	got ref -r $testroot/repo -c refs/heads/master \
+		refs/remotes/origin/master >/dev/null
+	
+	got checkout -b master $testroot/repo $testroot/wt >/dev/null
+
+	(cd $testroot/wt && got rebase origin/master > $testroot/stdout \
+		2> $testroot/stderr)
+	ret=$?
+	if [ $ret -eq 0 ]; then
+		echo "rebase succeeded unexpectedly" >&2
+		test_done "$testroot" "1"
+		return 1
+	fi
+	echo -n "got: will not rebase a branch which lives outside the " \
+		> $testroot/stderr.expected
+	echo '"refs/heads/" reference namespace' >> $testroot/stderr.expected
+	cmp -s $testroot/stderr.expected $testroot/stderr
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		diff -u $testroot/stderr.expected $testroot/stderr
+	fi
+	test_done "$testroot" "$ret"
+}
+
 test_parseargs "$@"
 run_test test_rebase_basic
 run_test test_rebase_ancestry_check
@@ -1673,3 +1700,4 @@ run_test test_rebase_delete_missing_file
 run_test test_rebase_rm_add_rm_file
 run_test test_rebase_resets_committer
 run_test test_rebase_no_author_info
+run_test test_rebase_nonbranch