wxGUI: report g.extension error

       (merge https://trac.osgeo.org/grass/changeset/59766 from trunk)


git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@59767 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/modules/extensions.py

@@ -305,11 +305,11 @@ class ExtensionTreeModelBuilder:
             flags = 'g'
         else:
             flags = 'l'
-        ret = RunCommand('g.extension', read = True,
-                         svnurl = url,
-                         flags = flags, quiet = True)
-        if not ret:
-            raise GException(_("Unable to load extensions."))
+        retcode, ret, msg = RunCommand('g.extension', read = True, getErrorMsg = True,
+                                       svnurl = url,
+                                       flags = flags, quiet = True)
+        if retcode != 0:
+            raise GException(_("Unable to load extensions. %s") % msg)
         
         currentNode = None
         for line in ret.splitlines():