lfs: infer the blob store URL from paths.default If `lfs.url` is specified, it takes precedence. However, now that we support serving blobs via hgweb, we shouldn't *require* this setting. Less configuration is better (things will work out of the box once this is sorted out), and git has similar functionality. This is not a complete solution- it isn't able to infer the blob store from an explicitly supplied path, and it should consider `paths.default-push` for push. The pull solution for that is a bit hacky, and this alone is an improvement for the vast majority of cases. Even though there are only a handful of references to the saved remote store, the location of them makes things complicated. 1) downloading files on demand in the revlog flag processor 2) copying to readonlyvfs with bundlerepo 3) downloading in the file prefetch hook 4) the canupload()/skipdownload() checks 5) uploading blobs Since revlog doesn't have a repo or ui reference, we can't avoid creating a remote store when the extension is loaded. While the long term goal is to make sure the prefetch hook is invoked early for every command for efficiency, this handling in the flag processor is needed as a last ditch fetch. In order to support the clone command, the remote store needs to be created later than when the extension loads, since `paths.default` isn't set until just before the files are checked out. Therefore, this patch changes the prefetch hook to ignore the saved reference, and build a new one. The canupload()/skipdownload() checks simply check if the stored instance is a `_nullremote`. Since this can only be set via `lfs.url` (which is reflected in the saved reference), checking only the instance created when the extension loaded is fine. The blob uploading function is called from several places: 1) a prepush hook 2) when writing a new bundle 3) from infinitepush The prepush hook gets an exchange.pushop, so it has a path to where the push is going. The bundle writer and infinitepush don't. Further, bundle creation for things like strip and amend are causing blobs to be uploaded. This seems wrong, but I don't want to side track this sorting that out, so punt on trying to handle explicit push paths or `paths.default-push`. I also think that sending blobs to a remote store when pushing to a local repo is wrong. This functionality predates the usercache, so perhaps that's the reason for it. I've got some patches floating around to stop sending blobs remotely in this case, and instead write directly to the other repo's blob store. But the tests for corruption handling weren't happy with this change, and I don't have time to rewrite them. So exclude filesystem based paths from this for now. I don't think there's much of a chance to implement `paths.remote:lfsurl` style configs, given how early these are resolved vs how late the remote store is created. But git has it, so I threw a TODO in there, in case anyone has ideas. I have no idea why this is now doing http auth twice when it wasn't before. I don't think the original blobstore's url is ever being used in these cases.