lfs: bypass wrapped functions when reposetup() hasn't been called (issue5902) There are only a handful of methods that access repo attributes that are applied in reposetup(). The `diff` test covers all of the commands that call scmutil.prefetchfiles(). Along the way, I saw that adding files and upgrading the repo format were also problems (also tested here). I don't think running `hg serve` through the commandserver is sane, but I conditionalized both the capabilities and the wsgirequest handler because it's trivially correct. It doesn't look like there has ever been a caller of candownload(), so there's no test for that path. The upload case isn't testable, because uploadblobs() bails if there are no pointers. The requirement should be added any time pointers are introduced, and that would force the extension to be loaded specifically for the repo. This covers `debuglfsupload`, the pre-push hook (which isn't set until the repo is promoted to LFS), and uploadblobsfromrevs(), which can be called by other extensions. I think readfromstore() and writetostore() are only reachable as a flag processor for revlog.REVIDX_EXTSTORED, and a requirement is added as soon as that is seen, so I don't think those are a problem.