When I run git add -p, I see:
git add -p
Can\'t locate Git.pm in @INC (@INC contains: /usr/local/lib/perl5/site_perl /Library/Perl/5.12/darwin-thread-multi-2lev
On macOS Mojave, git perl lib is in /Library/Developer/CommandLineTools/usr/share/git-core/perl. So, it can be fixed by:
/Library/Developer/CommandLineTools/usr/share/git-core/perl
export PERLLIB=/Library/Developer/CommandLineTools/usr/share/git-core/perl:$PERLLIB