fix: str2time rejects epoch -1 (Dec 31, 1969 23:59:59 UTC)

The epoch -1 detection logic compares parsed date components against
a hardcoded string to distinguish the legitimate -1 return value from
timegm/timelocal errors. However, since two-digit years are now
normalized to four-digit years before the timegm call, the comparison
always fails — the join produces "59592331111969" (year=1969) but the
check expected "595923311169" (year=69).

Fix: update the UTC check to use the 4-digit year string, and adjust
the local-time check to add 1900 to the localtime(-1) year component.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Koan-Bot

lib/Date/Parse.pm

@@ -303,7 +303,7 @@ sub str2time
      if !defined $result
         or $result == -1
            && join("",$ss,$mm,$hh,$day,$month,$year)
-                ne "595923311169";
+                ne "59592331111969";
    # Detect integer overflow: post-1970 dates must produce a non-negative epoch
    return undef if $result < 0 && $year >= 1970;
    $result -= $zone;
@@ -313,11 +313,13 @@ sub str2time
      local $SIG{__DIE__} = sub {}; # Ick!
      timelocal($ss,$mm,$hh,$day,$month,$year);
    };
+   my @_neg1 = localtime(-1);
+   $_neg1[5] += 1900;
    return undef
      if !defined $result
         or $result == -1
            && join("",$ss,$mm,$hh,$day,$month,$year)
-                ne join("",(localtime(-1))[0..5]);
+                ne join("",@_neg1[0..5]);
    # Detect integer overflow: post-1970 dates must produce a non-negative epoch
    # Use 1971 to avoid false positives from timezone offsets near epoch 0
    return undef if $result < 0 && $year >= 1971;

t/edge-cases.t

@@ -254,4 +254,24 @@ ok(!defined str2time("not a date at all"), "str2time('not a date at all') return
     }
 }
 
+# --- Epoch -1 (Dec 31, 1969 23:59:59 UTC) parsing ---
+# timegm() returns -1 for this date, which collides with Perl's error
+# convention.  str2time must distinguish the legitimate -1 from errors.
+{
+    my $t = str2time("31 Dec 1969 23:59:59 GMT");
+    is($t, -1, "epoch -1: 4-digit year with GMT");
+
+    my $t2 = str2time("1969-12-31T23:59:59Z");
+    is($t2, -1, "epoch -1: ISO 8601 with Z");
+
+    my $t3 = str2time("Wed, 31 Dec 1969 23:59:59 +0000");
+    is($t3, -1, "epoch -1: RFC 2822 with +0000");
+
+    my $t4 = str2time("31 Dec 69 23:59:59 GMT");
+    is($t4, -1, "epoch -1: 2-digit year with GMT");
+
+    my $t5 = str2time("1969-12-31 23:59:59 +0000");
+    is($t5, -1, "epoch -1: ISO with space separator");
+}
+
 done_testing;