RFR: pr: handle exceptions for commit commands

[Erik Helin]

Hi all,

please review this patch that properly handles `RuntimeException`s thrown by commit commands.

Testing:
- [x] `make test` passes on Linux x64

Thanks,
Erik

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Depends on: https://git.openjdk.java.net/skara/pull/1016

Commit messages:
 - pr: handle exceptions for commit commands

Changes: https://git.openjdk.java.net/skara/pull/1017/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1017&range=00
  Stats: 22 lines in 2 files changed: 10 ins; 6 del; 6 mod
  Patch: https://git.openjdk.java.net/skara/pull/1017.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1017/head:pull/1017

PR: https://git.openjdk.java.net/skara/pull/1017