[run-task] Support Git shallow clones

[ahal]

Supporting shallow clones in run-task would be a quick and easy win. This should probably even be the default behaviour.

[ahal]

Note, for caching purposes, you can run git fetch --unshallow to convert a shallow clone to a full one.

[CHARLIE1210-A]

Can you please define the issue. I am unable to understand what the actual problem is.