$NMBGIT .= '/.git' if (-d $NMBGIT.'/.git');
-my $TAGPREFIX = $ENV{NMBPREFIX} || 'notmuch::';
-
-# magic hash for git
-my $EMPTYBLOB = 'e69de29bb2d1d6434b8b29ae775ad8c2e48c5391';
+my $TAGPREFIX = defined($ENV{NMBPREFIX}) ? $ENV{NMBPREFIX} : 'notmuch::';
# for encoding
usage ();
}
+# magic hash for git
+my $EMPTYBLOB = git (qw{hash-object -t blob /dev/null});
+
&{$command{$subcommand}}(@ARGV);
sub git_pipe {