backends: don't detect backends when initializing db based vcs-instance.

This skips some calls back to vcsserver.

rhodecode/lib/vcs/backends/__init__.py

@@ -22,6 +22,7 b''
 VCS Backends module
 """
 
+import os
 import logging
 
 from pprint import pformat
@@ -42,11 +43,18 b' def get_vcs_instance(repo_path, *args, *'
     for the path it returns None. Arguments and keyword arguments are passed
     to the vcs backend repository class.
     """
+    explicit_vcs_alias = kwargs.pop('_vcs_alias', None)
     try:
-        vcs_alias = get_scm(repo_path)[0]
+        vcs_alias = explicit_vcs_alias or get_scm(repo_path)[0]
         log.debug(
             'Creating instance of %s repository from %s', vcs_alias, repo_path)
         backend = get_backend(vcs_alias)
+
+        if explicit_vcs_alias:
+            # do final verification of existance of the path, this does the
+            # same as get_scm() call which we skip in explicit_vcs_alias
+            if not os.path.isdir(repo_path):
+                raise VCSError("Given path %s is not a directory" % repo_path)
     except VCSError:
         log.exception(
             'Perhaps this repository is in db and not in '

rhodecode/model/db.py

@@ -1987,12 +1987,12 b' class Repository(Base, BaseModel):'
         custom_wire = {
             'cache': cache  # controls the vcs.remote cache
         }
-
         repo = get_vcs_instance(
             repo_path=safe_str(self.repo_full_path),
             config=config,
             with_wire=custom_wire,
-            create=False)
+            create=False,
+            _vcs_alias=self.repo_type)
 
         return repo