revset: move subscript relation functions to its own dict This will help adding more relation functions in extensions. We skip short names (that consist of one letter) while raising UnknownIdentifier because such names cannot be suggested anyway: the similarity cutoff in dispatch._getsimilar() is currently 0.6.

py3: teach run-tests.py to handle exe with spaces when --local isn't specified This was the reason that no amount of quoting worked in test-hghave.t. `os.popen()` needed to be swapped out because while the added quoting around line 3124 worked on py3, it failed on py2. See 38d51371792b. The problem with `os.system()` was wrongly splitting the command on the space in 'Program Files', regardless of quoting. It looks like there are a few other instances of `os.system()` in core code, so presumably those should be replaced?

rust: adapted hg-core tests for iteration over Result Now AncestorsIterator iters on Result<Revision, GraphError>

win32: close the handles associated with a spawned child process Probably not a big deal because at this point, the call is only used when spawning a daemonized server. In that case, the parent process goes away first, so it won't prevent the child from being cleaned up.

rust: remove comment about error handling of AncestorsIterator To be align with 443eb4bc41af "rust: propagate error of index_get_parents() properly." Spotted by Georges Racinet.

test: fix test-http-bad-server with current python 2.7 https://github.com/python/cpython/pull/2825 changed the exception message for empty http status line. Differential Revision: https://phab.mercurial-scm.org/D5412

perf: add perfprogress command I've noticed that progress bars can add significant overhead to tight loops. Let's add a perf command that attempts to isolate that overhead. With a default hgrc, iteration over 1M items appears to take ~3.75s on my machine. Profiling reveals ~28% of time is spent in ui.configbool() resolving the value of the progress.debug config option. Even if I set progress.disable=true, execution still takes ~2.60s, with ~59% of the time spent in ui.configbool(). Differential Revision: https://phab.mercurial-scm.org/D5407

wireprotov2: unify file revision collection and linknode derivation The old mechanism for choosing which file revisions to send in the haveparents=True case was buggy in multiple ways - the most severe of which being that file revisions were excluded when they shouldn't have been. This commit unifies the logic for deriving the filenodes that will be sent by the "filesdata" command. We now consistently read files data from manifests. The "haveparents" argument now controls whether we iterate ctx.files() or use the full manifest to derive relevant files. The logic here is still woefully lacking to fully support shallow clones. It will require an API break to fully address. This commit should at least make the server APIs emit proper data, which is strictly better than before. Differential Revision: https://phab.mercurial-scm.org/D5406

wireprotov2: send linknodes to emitfilerevisions() Previously, linknodes were calculated within emitfilerevisions() by using filectx.introrev(), which would always use the linkrev/linknode as recorded by storage. This is wrong for cases where the receiver doesn't have the changeset the linknode refers to. This commit changes the logic for linknode emission so the mapping of filenode to linknode is computed by the caller and passed into emitfilerevisions(). As part of the change, linknodes for "filesdata" in the haveparents=False case are now correct: the existing code performed a manifest walk and it was trivial to plug in the correct linknode. However, behavior for the haveparents=True case is still wrong because it relies on filtering linkrevs against the outgoing set in order to determine what to send. This will be fixed in a subsequent commit. The change test test-wireproto-exchangev2-shallow.t is a bit wonky. The test repo has 6 revisions. The changed test is performing a shallow clone with depth=1. So, only file data for revision 5 is present locally. So, the new behavior of associating the linknode with revision 5 for every file revision seems correct. Of course, when backfilling old revisions, we'll want to update the linknode. But this problem requires wire protocol support and we'll cross that bridge later. Differential Revision: https://phab.mercurial-scm.org/D5405

tests: add tests for server-side linknode adjustment with wireprotov2 The current implementation of linknode serving in wireprotov2 simply serves up the linkrev/linknode as stored: it doesn't attempt to adjust the linknode to what the receiver is aware of. This can result in the client seeing a linknode referencing a changeset that is unknown to it. This commit adds test coverage of that scenario. The tests in test-wireproto-command-filesdata.t demonstrate two failures. First, the linknode refers to a changeset not in the available set. Second, the server doesn't send a file revision that it should have (because of linkrev filtering). The test in test-wireproto-exchange.t demonstrates that the lack of a file revision results in a corrupted repository on the client. Differential Revision: https://phab.mercurial-scm.org/D5404