[Rev 02] RFR: Add pull request prune functionality

[Robin Westberg]

The pull request has been updated with additional changes.

----------------

Added commits:
 - fa681f06: Updated after feedback

Changes:
  - all: https://git.openjdk.java.net/skara/pull/247/files
  - new: https://git.openjdk.java.net/skara/pull/247/files/9983c27b..fa681f06

Webrevs:
 - full: https://webrevs.openjdk.java.net/skara/247/webrev.02
 - incr: https://webrevs.openjdk.java.net/skara/247/webrev.01-02

  Stats: 43 lines in 2 files changed: 35 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/skara/pull/247.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/247/head:pull/247

PR: https://git.openjdk.java.net/skara/pull/247