Merge branch '22229-use-base-sha-when-downloading-merge-requests' into 'master'
Use base SHA for patches and diffs ## What does this MR do? Switch from using 'start SHA' to 'base SHA' for patches and diffs ## Are there points in the code the reviewer needs to double check? ## Why was this MR needed? Makes the downloaded patches and diffs on the merge request page match the frontend-rendered "changes" in these scenarios: * Unpatched gitlab-workhorse, downloading patchsets of open MRs (https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/68) * Unpatched gitlab-workhorse, downloading diffs of open and merged MRs * Patched gitlab-workhorse, downloading patchsets of merged merge requests ## What are the relevant issue numbers? Closes #22229 See merge request !6435