Accept dates before 2000/01/01 when specified as seconds since the epoch

Tests with git-filter-branch on a repository that was converted from
CVS and that has commits reaching back to 1999 revealed that it is
necessary to parse dates before 2000/01/01 when they are specified
as seconds since 1970/01/01. There is now still a limit, 100000000,
which is 1973/03/03 09:46:40 UTC, in order to allow that dates are
represented as 8 digits.

Signed-off-by: Johannes Sixt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Johannes Sixt

date.c

@@ -414,9 +414,11 @@ static int match_digit(const char *date, struct tm *tm, int *offset, int *tm_gmt
 	num = strtoul(date, &end, 10);
 
 	/*
-	 * Seconds since 1970? We trigger on that for anything after Jan 1, 2000
+	 * Seconds since 1970? We trigger on that for any numbers with
+	 * more than 8 digits. This is because we don't want to rule out
+	 * numbers like 20070606 as a YYYYMMDD date.
 	 */
-	if (num > 946684800) {
+	if (num >= 100000000) {
 		time_t time = num;
 		if (gmtime_r(&time, tm)) {
 			*tm_gmt = 1;