[PATCH 3/3] git: reduce spawning for rev-parse --git-path

[Eric Wong <e@80x24.org>]

Since every non-worktree git repo has an `objects' directory, we
can quickly stat(2) to check for its presence and avoid an
expensive process spawn.  This should be the common case on
servers since it's rare to use worktrees on servers for
coderepos (or inboxes).
---
 lib/PublicInbox/Git.pm | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index 55005475..6b722023 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -108,9 +108,10 @@ sub new {
 sub git_path ($$) {
 	my ($self, $path) = @_;
 	$self->{-git_path}->{$path} //= do {
-		my $d = "$self->{git_dir}/$path";
-		if (-e $d) {
-			$d;
+		my $d = $self->{git_dir};
+		my $f = "$d/$path";
+		if (-d "$d/objects") {
+			$f;
 		} else {
 			local $/ = "\n";
 			my $rdr = { 2 => \my $err };
@@ -119,7 +120,7 @@ sub git_path ($$) {
 			chomp $s;
 
 			# git prior to 2.5.0 did not understand --git-path
-			$s eq "--git-path\n$path" ? $d : $s;
+			$s eq "--git-path\n$path" ? $f : $s;
 		}
 	};
 }