imagefetcher: Better error message for incorrect --location

Author: crobinso

virtinst/ImageFetcher.py

@@ -44,9 +44,11 @@ def _make_path(self, filename):
         else:
             path = self.location
 
-        if not path.endswith("/"):
-            path += "/"
-        path += filename
+        if filename:
+            if not path.endswith("/"):
+                path += "/"
+            path += filename
+
         return path
 
     def saveTemp(self, fileobj, prefix):

virtinst/OSDistro.py

@@ -106,8 +106,10 @@ def _storeForDistro(fetcher, baseuri, typ, progresscb, arch, distro=None,
         if store.isValidStore(fetcher, progresscb):
             return store
 
-    raise ValueError, _("Could not find an installable distribution at '%s'" %
-                        baseuri)
+    raise ValueError(
+        _("Could not find an installable distribution at '%s'\n"
+          "The location must be the root directory of an install tree." %
+          baseuri))
 
 def _locationCheckWrapper(guest, baseuri, progresscb,
                           scratchdir, _type, arch, callback):