Merge branch 'maint-1.5.1' into maint

* maint-1.5.1:
  git-svn: avoid md5 calculation entirely if SVN doesn't provide one
  Fix stupid typo in lookup_tag()

tag.c

@@ -26,7 +26,7 @@ struct tag *lookup_tag(const unsigned char *sha1)
 	if (!obj->type)
 		obj->type = OBJ_TAG;
         if (obj->type != OBJ_TAG) {
-                error("Object %s is a %s, not a tree",
+                error("Object %s is a %s, not a tag",
                       sha1_to_hex(sha1), typename(obj->type));
                 return NULL;
         }