As discussed earlier on irc, I noticed that symlinks that point outside
of the work tree are lost at least during update or histedit operations
even after using the -S flag to stage and commit the symlink. Below are
a few short scripts to reproduce what I tested (mostly the same commands
but I included all commands every time so that they are easy to copy
paste, hope that's okay).

# test update -c and update -b after stage and commit *with* -S
# expected: symlink survives operation
mkdir foo
echo "blah" > foo/bar
echo "blah" > file_out_of_tree
got init test.git
got import -r test.git/ -m'initial commit' foo/
got checkout test.git/
cd test
ln -sf ../file_out_of_tree .
got add file_out_of_tree
got sg -S file_out_of_tree
got commit -m 'symlink test' -S file_out_of_tree
got up -c :head:-1
got up -b main
cat file_out_of_tree
# output is target path (no EOL)

# test update -c and histedit -m after stage and commit *with* -S
# expected: symlink survives operation
mkdir foo
echo "blah" > foo/bar
echo "blah" > file_out_of_tree
got init test.git
got import -r test.git/ -m'initial commit' foo/
got checkout test.git/
cd test
ln -sf ../file_out_of_tree .
got add file_out_of_tree
got sg -S file_out_of_tree
got commit -m 'symlink test' -S file_out_of_tree
got up -c :head:-1
got histedit -m # edit commit message
# got: /path/to/file_out_of_tree: symbolic link points outside of paths under version control
got histedit -a # <-- file is lost
cat file_out_of_tree
# cat: file_out_of_tree: No such file or directory

# test update -c and update -b after stage and commit *without* -S
# expected: symlink is lost and file contains target path
mkdir foo
echo "blah" > foo/bar
echo "blah" > file_out_of_tree
got init test.git
got import -r test.git/ -m'initial commit' foo/
got checkout test.git/
cd test
ln -sf ../file_out_of_tree .
got add file_out_of_tree
got sg file_out_of_tree
got commit -m 'symlink test' file_out_of_tree
got up -c :head:-1 # <-- merge conflict here
got up -b main
cat file_out_of_tree
# merge conflict (symlink was deleted)

Not sure my expectations are correct, but overall the results seem
inconsistent to me. Please let me know if there's anything else you'd
like me to test.

Johannes