shortlog: fix segfault on empty authorname

The old code looked backwards from the email address to parse the name,
allowing an arbitrary number of spaces between the two. However, in the case
of no name, we looked back too far to the 'author' (or 'Author:') header.
Instead, remove at most one space between name and address.

The bug was triggered by commit febf7ea4bed from linux-2.6.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-shortlog.c

@@ -188,7 +188,7 @@ static void read_from_stdin(struct path_list *list)
 				bob = buffer + strlen(buffer);
 			else {
 				offset = 8;
-				while (isspace(bob[-1]))
+				if (isspace(bob[-1]))
 					bob--;
 			}
 
@@ -236,7 +236,7 @@ static void get_from_rev(struct rev_info *rev, struct path_list *list)
 					author = scratch;
 					authorlen = strlen(scratch);
 				} else {
-					while (bracket[-1] == ' ')
+					if (bracket[-1] == ' ')
 						bracket--;
 
 					author = buffer + 7;