hash-object: cleanup handling of command line options

git hash-object used to process the --stdin command line argument
before reading subsequent arguments.  This caused 'git hash-object
--stdin -w' to fail to actually write the object into the
database, while '-w --stdin' properly did.  Now git hash-object
first reads all arguments, and then processes them.

This regresses one insane use case.  git hash-object used to allow
multiple --stdin arguments on the command line:

   $ git hash-object --stdin --stdin
     foo
     ^D
     bar
     ^D

Now git hash-object errors out if --stdin is given more than once.

Reported by Josh Triplett through
 http://bugs.debian.org/464432

Signed-off-by: Gerrit Pape <pape@smarden.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

hash-object.c

@@ -41,6 +41,7 @@ int main(int argc, char **argv)
 	const char *prefix = NULL;
 	int prefix_length = -1;
 	int no_more_flags = 0;
+	int hashstdin = 0;
 
 	git_config(git_default_config);
 
@@ -65,13 +66,20 @@ int main(int argc, char **argv)
 			else if (!strcmp(argv[i], "--help"))
 				usage(hash_object_usage);
 			else if (!strcmp(argv[i], "--stdin")) {
-				hash_stdin(type, write_object);
+				if (hashstdin)
+					die("Multiple --stdin arguments are not supported");
+				hashstdin = 1;
 			}
 			else
 				usage(hash_object_usage);
 		}
 		else {
 			const char *arg = argv[i];
+
+			if (hashstdin) {
+				hash_stdin(type, write_object);
+				hashstdin = 0;
+			}
 			if (0 <= prefix_length)
 				arg = prefix_filename(prefix, prefix_length,
 						      arg);
@@ -79,5 +87,7 @@ int main(int argc, char **argv)
 			no_more_flags = 1;
 		}
 	}
+	if (hashstdin)
+		hash_stdin(type, write_object);
 	return 0;
 }