cindex: --prune needs git 2.6+

Older versions of git lack --batch-all-objects, and 2.6+ is
new enough already since v2, lei, etc all depend on it.

1 files changed, 1 insertions, 0 deletions

diff --git a/t/cindex.t b/t/cindex.t
index ab4cde7c..e5f26ec3 100644
--- a/t/cindex.t
+++ b/t/cindex.t
@@ -209,6 +209,7 @@ EOM
 
 SKIP: { # --prune
         require_cmd($ENV{XAPIAN_DELVE} || 'xapian-delve', 1);
+        require_git v2.6, 1;
         my $csrch = PublicInbox::CodeSearch->new("$tmp/ext");
         is(scalar($csrch->mset('s:hi')->items), 1, 'got hit');