wwwlisting: do not rely on $? after ProcessPipe::CLOSE

ProcessPipe::CLOSE won't reliably set $? inside the event loop
if waitpid(..., WNOHANG) isn't successful.  So use a blocking
waitpid() call, here, and hope "git show-ref" exits promptly
since we've already drained its stdout.

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/PublicInbox/WwwListing.pm b/lib/PublicInbox/WwwListing.pm
index bcb968af..e19ae8a1 100644
--- a/lib/PublicInbox/WwwListing.pm
+++ b/lib/PublicInbox/WwwListing.pm
@@ -127,7 +127,9 @@ sub _json () {
 
 sub fingerprint ($) {
         my ($git) = @_;
-        my $fh = $git->popen('show-ref') or
+        # TODO: convert to qspawn for fairness when there's
+        # thousands of repos
+        my ($fh, $pid) = $git->popen('show-ref') or
                 die "popen($git->{git_dir} show-ref) failed: $!";
 
         my $dig = Digest::SHA->new(1);
@@ -135,6 +137,7 @@ sub fingerprint ($) {
                 $dig->add($buf);
         }
         close $fh;
+        waitpid($pid, 0);
         return if $?; # empty, uninitialized git repo
         $dig->hexdigest;
 }