dispatch: catch InterventionRequired and print the message with no prefix

mercurial/dispatch.py

@@ -151,6 +151,8 b' def _runcatch(req):'
             commands.help_(ui, inst.args[0], unknowncmd=True)
         except error.UnknownCommand:
             commands.help_(ui, 'shortlist')
+    except error.InterventionRequired, inst:
+        ui.warn("%s\n" % inst)
     except util.Abort, inst:
         ui.warn(_("abort: %s\n") % inst)
         if inst.hint: