[PATCH] fix date parsing for GIT raw commit timestamp format.

Usually all of the match_xxx routines in date.c fill tm
structure assuming that the parsed string talks about local
time, and parse_date routine compensates for it by adjusting the
value with tz offset parsed out separately.  However, this logic
does not work well when we feed GIT raw commit timestamp to it,
because what match_digits gets is already in GMT.

A good testcase is:

    $ make test-date
    $ ./test-date 'Fri Jun 24 16:55:27 2005 -0700' '1119657327 -0700'

These two timestamps represent the same time, but the second one
without the fix this commit introduces gives you 7 hours off.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

date.c

@@ -270,7 +270,7 @@ static int match_multi_number(unsigned long num, char c, char *date, char *end,
 /*
  * We've seen a digit. Time? Year? Date? 
  */
-static int match_digit(char *date, struct tm *tm, int *offset)
+static int match_digit(char *date, struct tm *tm, int *offset, int *tm_gmt)
 {
 	int n;
 	char *end;
@@ -283,8 +283,10 @@ static int match_digit(char *date, struct tm *tm, int *offset)
 	 */
 	if (num > 946684800) {
 		time_t time = num;
-		if (gmtime_r(&time, tm))
+		if (gmtime_r(&time, tm)) {
+			*tm_gmt = 1;
 			return end - date;
+		}
 	}
 
 	/*
@@ -389,7 +391,7 @@ static int match_tz(char *date, int *offp)
 void parse_date(char *date, char *result, int maxlen)
 {
 	struct tm tm;
-	int offset, sign;
+	int offset, sign, tm_gmt;
 	time_t then;
 
 	memset(&tm, 0, sizeof(tm));
@@ -398,6 +400,7 @@ void parse_date(char *date, char *result, int maxlen)
 	tm.tm_mday = -1;
 	tm.tm_isdst = -1;
 	offset = -1;
+	tm_gmt = 0;
 
 	for (;;) {
 		int match = 0;
@@ -410,7 +413,7 @@ void parse_date(char *date, char *result, int maxlen)
 		if (isalpha(c))
 			match = match_alpha(date, &tm, &offset);
 		else if (isdigit(c))
-			match = match_digit(date, &tm, &offset);
+			match = match_digit(date, &tm, &offset, &tm_gmt);
 		else if ((c == '-' || c == '+') && isdigit(date[1]))
 			match = match_tz(date, &offset);
 
@@ -430,7 +433,8 @@ void parse_date(char *date, char *result, int maxlen)
 	if (then == -1)
 		return;
 
-	then -= offset * 60;
+	if (!tm_gmt)
+		then -= offset * 60;
 
 	sign = '+';
 	if (offset < 0) {