--- rabbitvcs-e8214e6e84e3b9e13fb551939e2fa8d27ceb7357/rabbitvcs/ui/log.py.old	2016-02-01 23:32:49.977770035 +0100
+++ rabbitvcs-e8214e6e84e3b9e13fb551939e2fa8d27ceb7357/rabbitvcs/ui/log.py	2016-02-01 23:32:54.664821439 +0100
@@ -1643,9 +1643,16 @@
 }
 
 def log_factory(path, vcs):
+    # vcs option is allowed for URL only
+    if os.path.exists(path):
+        vcs = None
+
     if not vcs:
         guess = rabbitvcs.vcs.guess(path)
         vcs = guess["vcs"]
+        if not classes_map.has_key(vcs):
+            from rabbitvcs.ui import VCS_OPT_ERROR
+            raise SystemExit(VCS_OPT_ERROR)
 
     return classes_map[vcs](path)