v.db.join: cache exception from vector_layer_db() - usually when vector map not found (merge https://trac.osgeo.org/grass/changeset/68261 from trunk)

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@68262 15284696-431f-4ddb-bdfa-cd5b030d7da7

scripts/v.db.join/v.db.join.py

@@ -73,8 +73,11 @@ def main():
     else:
         scolumns = None
 
-    f = grass.vector_layer_db(map, layer)
-
+    try:
+        f = grass.vector_layer_db(map, layer)
+    except CalledModuleError:
+        sys.exit(1)
+        
     maptable = f['table']
     database = f['database']
     driver   = f['driver']