shelve: handle empty parents and nodestoremove in shelvedstate (issue6748)

rhg: fallback when encountering ellipsis revisions Ellipsis revisions are still experimental and buggy in non-trivial histories. We currently have no plans to improve this situation nor to add support for ellipsis revisions in `rhg`. Falling back should be done carefully (since we may have already done some work that is visible to the user), but in this case it's highly unlikely that we're doing anything useful with a repo with ellipsis revisions, so this should be strictly better, also since the error message is more explicit.

dirstate-v2: hash the source of the ignore patterns as well Fixes the test introduced in the last changeset. This caused the hash to change, which means that the check in the test had to be adapted. Since this hash is only done as a caching mechanism, invalidation does not pose any backwards compatibility issues.

dirstate-v2: add test that shows a collision in ignore patterns hash This hash is used for optimizing dirstate `status`. We demonstrate that the hash is incorrectly ignoring the changes to the semantics of the ignore files just because the contents (but not their source) haven't changed. This is fixed in the next changeset.

testlib: add `--raw-sha1` option to `f` This will be used in the patch fixing the ignore hash collision in dirstate-v2 to check the behavior of the new hashing function.

rust-status: save new dircache even if just invalidated There was a functional race between invalidating the cache (not acted upon until the end of the status algorithm) and populating the new cache (which relies upon an up-to-date version of the cache). We simply inform the cache populating function that we've just invalidated the cache for this particular directory since the information is present in the same scope.

rust-status: fix typos and add docstrings to dircache related fields

rhg: show a bug where repeated [hg status] is needed to cache everything

upgrade: no longer keep all revlogs in memory at any point Keeping all object open is unsustainable, so we will open them on demand. This mean opening them multiple times, but this is a lesser evil. Each revlog consume a small amount of memory (index content, associated nodemap, etc). While there are few "big" revlog, the sheer amount of small filelog can become a significant issue memory wise, consuming multiple GB of memory. If you combines this extra usage with the use of multiprocessing, this usage can quickly get out of control. This can effectively block the upgrade of larger repository. This changeset fixes this issue.

demandimport: convert ignored modules from bytes -> str in extensions The default list of ignored modules are str, and test for bypassing the lazy import is `module.__name__ in ignores`, so these were effectively NOT ignored. Most of these date back to the grand byteification in 687b865b95ad, with some subsequent additions that followed the existing example. I have no idea if these modules in fact need to bypass lazy importing, but at least it follows the intent of the code.