Add error message for download -c conflicts

Currently if you run repo download -c on a change and the cherry-pick
runs into a merge conflict a Traceback is produced:

rob@rob-i5-lm ~/Programming/repo_test/repo1 $ repo download -c repo1 3/1
From ssh://rob-i5-lm:29418/repo1
 * branch            refs/changes/03/3/1 -> FETCH_HEAD
error: could not apply 0c8b474... 2
hint: after resolving the conflicts, mark the corrected paths
hint: with 'git add <paths>' or 'git rm <paths>'
hint: and commit the result with 'git commit'
Traceback (most recent call last):
  File "/home/rob/Programming/git-repo/main.py", line 408, in <module>
    _Main(sys.argv[1:])
  File "/home/rob/Programming/git-repo/main.py", line 384, in _Main
    result = repo._Run(argv) or 0
  File "/home/rob/Programming/git-repo/main.py", line 143, in _Run
    result = cmd.Execute(copts, cargs)
  File "/home/rob/Programming/git-repo/subcmds/download.py", line 90, in Execute
    project._CherryPick(dl.commit)
  File "/home/rob/Programming/git-repo/project.py", line 1943, in _CherryPick
    raise GitError('%s cherry-pick %s ' % (self.name, rev))
error.GitError: repo1 cherry-pick 0c8b4740f876f8f8372bbaed430f02b6ba8b1898

This amount of error message is confusing to users and has the side effect
of the git message telling you the actual issue being ignored.

This change introduces a message stating that the cherry-pick couldn't
be completed removing the Traceback.

To reproduce the issue create a change that causes a conflict with one currently
in review and use repo download -c to cherry-pick the conflicting change.

Change-Id: I8ddf4e0c8ad9bd04b1af5360313f67cc053f7d6a

0 files changed, 0 insertions, 0 deletions