record: removed 'has_key' usage
Py3k has removed the dictionary has_key method. This patch implements
a one argument function that can be used as a callback by hg.revert in
the record extension.
% fail
abort: inotify-server: cannot start: .hg/inotify.sock is a broken symlink
inotify-client: could not start inotify server: child process failed to start
abort: inotify-server: cannot start: .hg/inotify.sock is a broken symlink
% inserve
% status
? hg.pid