git: avoid Perl5 internal scratchpad target cache

Creating a scalar ref directly off substr() seemed to be causing
the underlying non-ref scalar to end up in Perl's scratchpad.
Assign the substr result to a local variable seems sufficient to
prevent multi-megabyte SVs from lingering indefinitely when a
read-only daemon serves rare, oversized blobs.

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index 374a3b4d..4078dd5b 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -158,7 +158,8 @@ sub my_read ($$$) {
                         return; # unrecoverable error
                 }
         }
-        \substr($$rbuf, 0, $len, '');
+        my $no_pad = substr($$rbuf, 0, $len, '');
+        \$no_pad;
 }
 
 sub my_readline ($$) {