tests: quiet down commit graph

Newer versions of git enable the commit graph by default.
Since we blow away our temporary directories every test,
generating graphis is a waste and clutters stderr with
"Computing commit graph generation numbers" messages.

1 files changed, 1 insertions, 0 deletions

diff --git a/t/purge.t b/t/purge.t
index 12644d69..db09b731 100644
--- a/t/purge.t
+++ b/t/purge.t
@@ -11,6 +11,7 @@ foreach my $mod (@mods) {
         plan skip_all => "missing $mod for t/purge.t" if $@;
 };
 use Cwd qw(abs_path); # we need this since we chdir below
+local $ENV{HOME} = abs_path('t');
 my $purge = abs_path('blib/script/public-inbox-purge');
 my ($tmpdir, $for_destroy) = tmpdir();
 use_ok 'PublicInbox::V2Writable';