HTTP error 203 when pushing

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Reproduction steps

I have a docker machine that is supposed to push some files. I am using a PAT to push to the private repo. When I try this locally it works. But on the docker machine I get this error:

LibGit2Sharp.LibGit2SharpException: unexpected HTTP status code: 403
\n at LibGit2Sharp.Core.Ensure.HandleError(Int32 result)
\n at LibGit2Sharp.Core.Proxy.git_remote_push(RemoteHandle remote, IEnumerable1 refSpecs, GitPushOptions opts)\n at LibGit2Sharp.Network.Push(Remote remote, IEnumerable1 pushRefSpecs, PushOptions pushOptions)
\n at Project.Controllers.upload.UploadController.Upload(String id) in /src/Project/src/Project/Controllers/upload/UploadController.cs:line 63

Expected behavior

Expected behavior is for this to work on both local and docker machines

Actual behavior

It only works locally

Version of LibGit2Sharp (release number or SHA1)

I tried a couple versions. All gave the same result. Now I am on 0.27.0-preview-0034

Operating system(s) tested; .NET runtime tested

MacOS working fine. Docker linux agent does not

Start at the reported call chain through Project/Controllers/upload/UploadController.cs:63, LibGit2Sharp.Core.Ensure.HandleError, Core.Proxy.git_remote_push, and Network.Push. Reproduce the same PAT-backed push on macOS and the Docker Linux agent using LibGit2Sharp 0.27.0-preview-0034, then identify why the environments return different HTTP statuses and verify pushing works consistently.