commandserver: reset state of progress bar per command

A progress bar is normally disabled in command-server session, but chg can
enable it. This patch makes sure the last-print time is measured per command.
Otherwise, progress.delay could be ineffective if a progbar was loaded before
forking worker process.

This patch is corresponding to the following change.

https://bitbucket.org/yuja/chg/commits/2dfe3e90b365

mercurial/commandserver.py

@@ -214,6 +214,11 b' class server(object):'
             self.repo.ui = self.repo.dirstate._ui = repoui
             self.repo.invalidateall()
 
+        # reset last-print time of progress bar per command
+        # (progbar is singleton, we don't have to do for all uis)
+        if copiedui._progbar:
+            copiedui._progbar.resetstate()
+
         for ui in uis:
             # any kind of interaction must use server channels, but chg may
             # replace channels by fully functional tty files. so nontty is