Source hydrator fails with "Invalid revision range"

[crenshaw-dev]

Describe the bug

Hydration fails with an error like this:

Failed to hydrate revision "": failed to hydrate apps: failed to get repo objects: failed to get repo objects: failed to compare revisions for source 1 of 1: rpc error: code = Internal desc = unable to get changed files for repo https://github.com/org/repo.git with revision b6005465335e883927fe8b5ce0fd513fd4e75ec3: failed to diff b71323f97523272c4222932e9113a4d81f9f32ea..b6005465335e883927fe8b5ce0fd513fd4e75ec3: `git diff --name-only b71323f97523272c4222932e9113a4d81f9f32ea..b6005465335e883927fe8b5ce0fd513fd4e75ec3` failed exit status 128: fatal: Invalid revision range b71323f97523272c4222932e9113a4d81f9f32ea..b6005465335e883927fe8b5ce0fd513fd4e75ec3

The problem seems to be related to the fact that the first hash represents a commit on the dry branch, and the second hash represents a hash on the hydrated branch. The two aren't really comparable.

To Reproduce

This seems to randomly happen on any app that uses the manifest-generate-paths annotation.

I think it's flaky because the failure depends on a discrepancy between the state of the cached repo-server repo clone and the upstream repo. If the repo-server hasn't pulled either the dry or hydrated commit being compared, it will fail.

Expected behavior

The source hydrator shouldn't compare dry and hydrated commits for work-avoidance when manifest-generate-paths is specified. The hydrator doesn't even really support that annotation yet. We should just drop the annotation when doing hydration.