Mercurial 4.0 release

This is a draft and may not accurately reflect what lands in the 4.0 release.

1. Features

2. Improvements

3. Raw draft changelog

3.1. commands

• annotate: calculate line count correctly
• branchmap: acquires lock before writting the rev branch cache
• branchmap: simplify error handlind when writing rev branch cache

• commit: return 1 for interactive commit with no changes (issue5397)

• config: add template support
• copy: distinguish "file exists" cases and add a hint (BC)
• debugextension: change "testedwith" to a list (BC)
• debugextensions: hide "ships-with-hg-core" magic string (BC)

• debugobsolete: add formatter support (issue5134)

• debugrevspec: deprecate --optimize option

• files: change documentation to match its behaviour (issue5276)

• flags: allow specifying --no-boolean-flag on the command line (BC)
• graphlog: preserve topo sort even if additional filter options specified
• grep: add formatter support
• grep: build list of all columns regardless of display options

• help: show content for explicitly disabled extension (issue5228)

• import: abort instead of crashing when copy source does not exist (issue5375)

• import: report directory-relative paths in error messages (issue5224)

• log: copy the way of ancestor traversal to --follow matcher (issue5376)

• log: drop hack to fix order of revset (issue5100)

• log: drop outdated optimization to walk revisions in reverse order
• log: unroll loop that populates file paths for --patch --follow matcher
• merge: add conflict labels to merge command
• pull: grab wlock during pull

3.2. core

• auditvfs: forward options property from nested vfs
• bundle2: remove 'experimental.bundle2-exp' boolean config (BC)
• bundlerepo: add support for treemanifests in cg3 bundles
• changelog: disable delta chains
• changelog: specify checkambig=True to avoid ambiguity around truncation

• copies: make _checkcopies handle copy sequences spanning the TCA (issue4028)

• demandimport: add 'nt' to ignore list (issue5373)

• demandimport: add trailing comma

• demandimport: error out early on missing attribute of non package (issue5373)

• demandimport: import sub-module relatively as expected (issue5208)

• demandimport: omit default value of "level" at construction of _demandmod
• deprecation: enforce thew 'tr' argument of 'dirstate.write' (API)
• dispatch: explicitly pass fancyopts optional arg as a keyword
• dispatch: set profiling.enabled when profiling is enabled
• exchange: refactor APIs to obtain bundle data (API)
• extdiff: isolate path variable of saved command to independent paragraph

• formatter: add function to convert list to appropriate format (issue5217)

• formatter: introduce isplain() to replace (the inverse of) nonzero() (API)

• getchangegroup: take an 'outgoing' object as argument (API)

• hg: set default path correctly when doing a clone+share (issue5378)

• localrepo: make invalidate avoid invalidating store inside transaction (API)

• lock: show more detail for new-style locks in lock waiting message (issue4752)

• match: remove matchessubrepo method (API)
• mpatch: change Py_ssize_t to ssize_t in places that will be later copied
• mpatch: change lalloc() to local function
• mpatch: provide things that will be exported later with a prefixed name

• mpatch: raise MemoryError instead of mpatchError if lalloc() failed

• mpatch: remove dependency on Python.h in mpatch.c
• mpatch: silence warning about maybe-uninitialized variable
• mpatch: write a cffi version of mpatch.patches
• profiling: make profiling functions context managers (API)
• profiling: move profiling code from dispatch.py (API)
• py3: test to check which commands run
• revlog: add instance variable controlling delta chain use
• revlog: make code in builddelta() slightly easier to read
• revlog: specify checkambig at writing to avoid file stat ambiguity
• revlog: use an LRU cache for delta chain bases
• revset: add option to make matcher takes the ordering of the input set

• revset: do not rewrite ':y' to '0:y' (issue5385)

• revset: fix order of nested '_(|int|hex)list' expression (BC)
• revset: fix order of nested 'or' expression (BC)
• revset: fix order of nested 'range' expression (BC)
• revset: make reverse() noop depending on ordering requirement (BC)
• revset: make sort() noop depending on ordering requirement (BC)

• revset: support "follow(renamed.py, e22f4f3f06c3)" (issue5334)

• ssl: handle a difference in SSLError with pypy (issue5348)

• streamclone: clear caches after writing changes into files for visibility
• streamclone: force @filecache properties to be reloaded from file

• template: provide a termwidth keyword (issue5395)

• templater: add inheritance support to style maps

• templater: add relpath() to convert repo path to relative path (issue5394)

• templater: make pad() evaluate boolean argument (BC)
• util: rename checkcase() to fscasesensitive() (API)
• version: add formatter support
• wireproto: remove gboptslist (API)
• wireproto: unescape argument names in batch command (BC)

3.3. extensions

• journal: properly check for held lock (issue5349)

• journal: use fm.formatdate() to pass date tuple in appropriate type (BC)
• journal: use fm.formatlist() to pass hashes in appropriate type (BC)
• journal: use fm.hexfunc() to get full hash in JSON/template output (BC)
• largefiles: always use filechunkiter when iterating files
• largefiles: fix 'deleted' files sometimes persistently appearing with R status
• largefiles: more safe handling of interruptions while updating modifications
• largefiles: test coverage of fatal interruption of update
• largefiles: use context for file closing
• largefiles: when setting/clearing x bit on largefiles, don't change other bits
• mq: release lock after transaction in qrefresh
• mq: take wlock when 'qqueue' is doing write operations
• mq: use single quotes in use warning
• rebase: make debug logging more consistent

• rebase: properly calculate total commits to rebase (issue5347)

• rebase: rebase changesets in topo order (issue5370) (BC)

• rebase: use single quotes in use warning

• strip: report both bundle files in case of exception (issue5368)

3.4. hgweb

• hgweb: avoid line wrap between revision and annotate-info (issue5398)

• hgweb: config option to control zlib compression level