import: allow the epoch (0s) as a valid time

Despite email not existing until 1971; "Jan 1, 1970 00:00:00"
seems like a common default timestamp for some test emails
to use as a Date: header.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/PublicInbox/Import.pm b/lib/PublicInbox/Import.pm
index f8d10037..1f831a7b 100644
--- a/lib/PublicInbox/Import.pm
+++ b/lib/PublicInbox/Import.pm
@@ -233,7 +233,7 @@ sub parse_date ($) {
                 warn "bogus TZ offset: $zone, ignoring and assuming +0000\n";
                 $zone = '+0000';
         }
-        $ts ||= time;
+        $ts = time unless defined $ts;
         $ts = 0 if $ts < 0; # git uses unsigned times
         "$ts $zone";
 }