Please backport screen 4.2.1-2 (main) from utopic

Please backport screen 4.2.1-2 (main) from utopic to trusty.

Reason for the backport:
========================
GNU Screen 4.2.1 is a newer upstream release, whereas the version of screen in Trusty is from three years ago (aside from distribution-specific patches).

Testing:
========
Mark off items in the checklist [X] as you test them, but please leave the checklist so that backporters can quickly evaluate the state of testing.

You can test-build the backport in your PPA with backportpackage:
$ backportpackage -u ppa:<lp username>/<ppa name> -s utopic -d trusty screen

* trusty:
[X] Package builds without modification
[X] screen-dbg installs cleanly and runs
[X] screen installs cleanly and runs

Reverse dependencies:
=====================
The following reverse-dependencies need to be tested against the new version of screen. For reverse-build-dependencies (-Indep), please test that the package still builds against the new screen. For reverse-dependencies, please test that the version of the package currently in the release still works with the new screen installed. Reverse- Recommends, Suggests, and Enhances don't need to be tested, and are listed for completeness-sake.

screen-dbg
----------

screen
------
* rtorrent
  [ ] trusty (Reverse-Suggests)
* surfraw
  [ ] trusty (Reverse-Suggests)
* epoptes-client
  [ ] trusty (Reverse-Depends)
* cereal
  [ ] trusty (Reverse-Depends)
* mdm
  [ ] trusty (Reverse-Depends)
* piuparts-slave
  [ ] trusty (Reverse-Depends)
* screenie
  [ ] trusty (Reverse-Depends)
* byobu
  [ ] trusty (Reverse-Recommends)
  [ ] trusty (Reverse-Depends)
  [ ] trusty (Reverse-Enhances)
* iselect
  [ ] trusty (Reverse-Suggests)
  [ ] trusty (Reverse-Enhances)
* podracer
  [ ] trusty (Reverse-Depends)
* ubuntu-remote-debug-host-tools
  [ ] trusty (Reverse-Depends)
* apt-dater
  [ ] trusty (Reverse-Depends)
* winpdb
  [ ] trusty (Reverse-Recommends)
* surfraw-extra
  [ ] trusty (Reverse-Suggests)