lfs: provide more Batch API error info via a hint in the raised exception A coworker had a typo in `lfs.url`, forgot it was even set because usually the blob server is inferred, and then got a 404. It would have been easier to debug with the failing URL printed.

scmutil: display the optional hint when handling StorageError in catchall() Other than CensoredNodeError (which is also a StorageError), it looks like all exceptions with a hint display them. I'm not sure that it makes sense to have a hint for censored nodes, so I'm not bothering with that. It looks like nobody is using this yet, as the tests don't change.

sparse-revlog: align endrevidx usages in the _slicechunktosize All "startrevidx..endrevidx" ranges in this function are now half-open.

graft: do not try to skip rev derived from ancestor more than once (issue6024) We check 'x in revs' in other cases, so let's do the same. The test case credits to Tom Prince.

subrepo: print the status line before creating the peer for better diagnostics I ran into a problem where I tried updating to a different branch, and the process appeared to hang. It turned out that the subrepo revision wasn't available locally, and I must have originally cloned it from an `hg serve -S` on a machine that currently wasn't serving anything. It took 2+ minutes to timeout, and didn't mention what it was connecting to even then. There are a couple of other issues in this scenario too. - The repo is dirty after the failed checkout because the top level repo is updated first. We should probably make 2 passes- top down to pull everything needed, and then do an update once everything is in place. - Something must be reading .hgsubstate from wdir because if the same merge command is run after the timeout, a prompt is issued that the local and remote subrepo diverged, instead of hanging. But it lists the local version and remote version as having the same hash.

sparse-revlog: use `span` variable as intended The variable was planned to be used in the while condition but was not used yet.