GitMergeExecutor: Use 'git reset --hard' instead of 'git pull'
GitMergeExecutor: Use 'git reset --hard' instead of 'git pull'

'git pull' has a chance to fail if the working directory is not in the
state we expect.

rudle/kochiku,moshez/kochiku,rudle/kochiku,moshez/kochiku,square/kochiku,square/kochiku,rudle/kochiku,moshez/kochiku,rudle/kochiku,moshez/kochiku,square/kochiku,square/kochiku