Returning a value that indicates the parking of a call was a success when it really wasn't (because the parking slot selected was in use) is the wrong thing to do. (issue #9723 reported by mdu113)

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@67064 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_features.c

@@ -328,7 +328,7 @@ int ast_park_call(struct ast_channel *chan, struct ast_channel *peer, int timeou
 			ast_mutex_unlock(&parking_lock);
 			free(pu);
 			ast_log(LOG_WARNING, "Requested parking extension already exists: %s@%s\n", parkingexten, parking_con);
-			return 0;	/* Continue execution if possible */
+			return -1; /* We failed to park this call, plain and simple so we need to error out */
 		}
 		ast_copy_string(pu->parkingexten, parkingexten, sizeof(pu->parkingexten));
 		x = atoi(parkingexten);