Prevent hang in git cat-file if repository is not a valid repository and other fixes (#17991)

This PR contains multiple fixes. The most important of which is:

* Prevent hang in git cat-file if the repository is not a valid repository 
    
    Unfortunately it appears that if git cat-file is run in an invalid
    repository it will hang until stdin is closed. This will result in
    deadlocked /pulls pages and dangling git cat-file calls if a broken
    repository is tried to be reviewed or pulls exists for a broken
    repository.

    Fix #14734
    Fix #9271
    Fix #16113

Otherwise there are a few small other fixes included which this PR was initially intending to fix:

* Fix panic on partial compares due to missing PullRequestWorkInProgressPrefixes
* Fix links on pulls pages  due to regression from #17551 - by making most /issues routes match /pulls too - Fix #17983
* Fix links on feeds pages due to another regression from #17551 but also fix issue with syncing tags - Fix #17943
* Add missing locale entries for oauth group claims
* Prevent NPEs if ColorFormat is called on nil users, repos or teams.

routers/web/repo/compare.go

@@ -685,6 +685,7 @@ func CompareDiff(ctx *context.Context) {
 		return
 	}
 
+	ctx.Data["PullRequestWorkInProgressPrefixes"] = setting.Repository.PullRequest.WorkInProgressPrefixes
 	ctx.Data["DirectComparison"] = ci.DirectComparison
 	ctx.Data["OtherCompareSeparator"] = ".."
 	ctx.Data["CompareSeparator"] = "..."
@@ -762,7 +763,6 @@ func CompareDiff(ctx *context.Context) {
 	ctx.Data["IsDiffCompare"] = true
 	ctx.Data["RequireTribute"] = true
 	ctx.Data["RequireEasyMDE"] = true
-	ctx.Data["PullRequestWorkInProgressPrefixes"] = setting.Repository.PullRequest.WorkInProgressPrefixes
 	setTemplateIfExists(ctx, pullRequestTemplateKey, nil, pullRequestTemplateCandidates)
 	ctx.Data["IsAttachmentEnabled"] = setting.Attachment.Enabled
 	upload.AddUploadContext(ctx, "comment")