+sub git_read_head {
+ my $project = shift;
+ my $oENV = $ENV{'GIT_DIR'};
+ my $retval = undef;
+ $ENV{'GIT_DIR'} = "$projectroot/$project";
+ if (open my $fd, "-|", "$gitbin/git-rev-parse", "--verify", "HEAD") {
+ my $head = <$fd>;
+ close $fd;
+ chomp $head;
+ if ($head =~ m/^[0-9a-fA-F]{40}$/) {
+ $retval = $head;
+ }
+ }
+ $ENV{'GIT_DIR'} = $oENV;
+ return $retval;
+}
+