dispatch: remove superfluous try/except when reading local ui config

ui.readconfig() already handles IOError in this case.

mercurial/dispatch.py

@@ -419,11 +419,8 b' def _getlocal(ui, rpath):'
     if not path:
         lui = ui
     else:
-        try:
-            lui = ui.copy()
-            lui.readconfig(os.path.join(path, ".hg", "hgrc"))
-        except IOError:
-            pass
+        lui = ui.copy()
+        lui.readconfig(os.path.join(path, ".hg", "hgrc"))
 
     if rpath:
         path = lui.expandpath(rpath[-1])