(#3757) re-introduce lockfile changes

This commit re-introduces the lockfile behavior changes that
were originally merged in to 2.7.x via this pull request:

https://github.com/puppetlabs/puppet/pull/216

It was reverted because of mcollective compatibility issues.
For more info see:

http://projects.puppetlabs.com/issues/12844

It is now being reintroduced for Telly, but with some minor
modifications. See #3757, #12933 and #12934 for details on those.