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.
adding a
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
a renamed from b:37d9b5d994eab34eda9c16b195ace52c7b129980
% test with --rev
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3