RFR: Avoid potentially moving folders across volume boundaries

[Robin Westberg]

When a checked out repository cannot be cleaned, the folder is moved to a separate location to allow further manual
inspection. Avoid moving them across volume boundaries.

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

Commit messages:
 - Avoid potentially moving folders across volume boundaries

Changes: https://git.openjdk.java.net/skara/pull/858/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=858&range=00
  Stats: 9 lines in 1 file changed: 0 ins; 8 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/858.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/858/head:pull/858

PR: https://git.openjdk.java.net/skara/pull/858