Wrap should always be enabled for parallel diff.
Update gitlab-grit to 2.6.11

From the gitlab-grit changelog:
  * Suppress 'unkown header' warnings
  * Add process.out to CommandFailed error
Merge branch 'gitlab-grit-2.6.11' into 'master'

Update gitlab-grit to 2.6.11

See merge request !1081
Merge branch 'wrap_by_default_for_parallel' into 'master'

Wrap by default for parallel

Fixes #1566

See merge request !1080