Fix typos / spelling in comments

Signed-off-by: Mike Ralphson <mike@abacus.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 0b0d6b8..63ac998 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -267,7 +267,7 @@
 			int score;
 			struct diff_filespec *source = p->filespec;
 
-			/* False hash collission? */
+			/* False hash collision? */
 			if (hashcmp(source->sha1, target->sha1))
 				continue;
 			/* Non-regular files? If so, the modes must match! */