lfs: fix blob corruption when tranferring with workers on posix The problem seems to be that the connection used to request the location of the blobs is sitting in the connection pool, and then when workers are forked, they all see and attempt to use the same connection. This garbles everything. I have no clue how this ever worked reliably (but it seems to, even on Linux, with SCM Manager 1.58). See previous discussion when worker support was added[1]. It shouldn't be a problem on Windows, since the workers are just threads in the same process, and can see which connections are marked available and which are in use. (The fact that `mercurial.keepalive.ConnectionManager.set_ready()` doesn't acquire a lock does give me some pause though.) [1] https://phab.mercurial-scm.org/D1568#31621

keepalive: add `__repr__()` to the HTTPConnection class to ease debugging By default, this just printed the class name and memory address. By displaying the address and ports on both sides of the socket, it makes it easier to figure out what's in the ConnectionManager, and correlate with WireShark traces. It looks like the two connections mentioned in the previous commit come about because the LFS POST request to access the blobs opens connection 1, and gets a 401. Then for some reason, the follow up with credentials opens a new socket, instead of using the existing one in the pool. I have no clue why. This can be seen with something like this in the blobstore: ``` for h in self.urlopener.handlers: if hasattr(h, "close_all"): print('open connections on %s in pid %d' % (type(h), os.getpid())) for host, conns in h._cm.get_all().items(): for c in conns: print('connection: %r' % c) ```

keepalive: ensure `close_all()` actually closes all cached connections While debugging why LFS blob downloads are getting corrupted with workers, I noticed that prior to spinning up the workers, the ConnectionManager has 2 connections to the server and calling `KeepAliveHandler.close_all()` left one behind. The reason is the value component of `self._cm.get_all().items()` is a list, and `self._cm.remove()` modifies said list while the caller is iterating over it. Now `get_all()` is a deep copy of both the dict and lists in all cases.

localrepo: byteify the requirements.DIRSTATE_TRACKED_HINT_Vx warning message Flagged by PyCharm.

rhg: fallback to slow path on invalid patterns in hgignore

rhg: add a test involving hgignore lookaround

relnotes: add 6.3

Added signature for changeset a3356ab610fc

Added tag 6.3rc0 for changeset a3356ab610fc

branching: merge default into stable This marks the feature freeze for the 6.3 release

shelve: re-wrap now that the line fits

shelve: avoid setting overloading tmpwctx