verify: allow the storage to signal when renames can be tested on `skipread` This applies the new marker in the lfs handler to show it in action, and adds the test mentioned at the beginning of the series to show that fulltext isn't necessary in the LFS case. The existing `skipread` isn't enough, because it is also set if an error occurs reading the revlog data, or the data is censored. It could probably be cleared, but then it technically violates the interface contract. That wouldn't matter for the existing verify algorithm, but it isn't clear how that will change as alternate storage support is added. The flag is probably pretty revlog specific, given the comments in verify.py. But there's already filelog specific stuff in there and I'm not sure what future storage will bring, so I don't want to over-engineer this. Likewise, I'm not sure that we want the verify method for each storage type to completely drive the bus when it comes to detecting renames, so I don't want to go down the rabbithole of having verifyintegrity() return metadata hints at this point. Differential Revision: https://phab.mercurial-scm.org/D7713

lfs: don't skip locally available blobs when verifying The `skipflags` config was introduced in a2ab9ebcd85b, which specifically calls out downloading and storing all blobs as potentially too expensive. But I don't see any reason to skip blobs that are already available locally. Hashing the blob is the only way to indirectly verify the rawdata content stored in the revlog. (The note in that commit about skipping renamed is still correct, but the reason given about needing fulltext isn't.) Differential Revision: https://phab.mercurial-scm.org/D7712