server-info: skip empty lines.

Now we allow an empty line in objects/info/packs file, recognize
that and stop complaining.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/server-info.c b/server-info.c
index 6089765..05bce7d 100644
--- a/server-info.c
+++ b/server-info.c
@@ -99,7 +99,10 @@
 	while (fgets(line, sizeof(line), fp)) {
 		int len = strlen(line);
 		if (line[len-1] == '\n')
-			line[len-1] = 0;
+			line[--len] = 0;
+
+		if (!len)
+			continue;
 
 		switch (line[0]) {
 		case 'P': /* P name */