remove superfluous newlines in error messages

The error handling routines add a newline.  Remove
the duplicate ones in error messages.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/unpack-trees.c b/unpack-trees.c
index 36523da..7cfa026 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -1792,7 +1792,7 @@
 	struct cache_entry *a = src[1];
 
 	if (o->merge_size != 1)
-		return error("Cannot do a bind merge of %d trees\n",
+		return error("Cannot do a bind merge of %d trees",
 			     o->merge_size);
 	if (a && old)
 		return o->gently ? -1 :