(Belatedly) Announcing Release 21 of the PostgreSQL Buildfarm Client

 This release was made 9 days ago, but I just realized that I neglected to make a blog post about it. So, for the record, here is the announcement that went out via email.

I have released version 21 of the PostgreSQL Buildfarm Client

New features

• PatchStack module — a new module for non-standard buildfarms that want to
  test a stack of patches on top of a branch. Note: this module is not for use with the
  regular community Buildfarm server - its use for builds reported there will be detected and rejected.
• ABI check module — a new module that runs abidw to detect ABI changes in
  installed headers (passes --headers-dir and --drop-private-types for
  compatibility across abidw versions). Original author: Mankirat Singh, with
  additions from Tom Lane.
• branches_target config key — run_branches.pl can now use a dedicated
  target URL for fetching branches_of_interest.json instead of deriving it by
  regex-mangling the main target URL. Falls back to the old derivation when
  unset; the pgbuildfarm URL migration is applied to it as well.

Build system / meson

• using_meson is now decided by the presence of meson.build rather than by
  branch name, so it works reliably with non-standard branch names.
• Use the meson --buildtype option.

Non-standard / regex-matched branches

• Skip the bf_ prefix when using regex-matched branches.
• Fetch remote branches for regex checking in a saner way.
• Handle cases where there is no usable symbolic HEAD (and suppress the
  resulting clone warnings).
• Handle a missing remote HEAD when updating a mirror.

Cross-version upgrade

• Compress pg_upgrade dump files
• Stop testing upgrades from pre-v10 in v20 and higher.
• Several pg_upgrade_output.d fixes, including relative-path logic and an
  output-collection bug.

Protocol

• Adjust to upstream libpq protocol-version changes, and remove the
  PGMAXPROTOCOLVERSION setting earlier (per -hackers discussion).

Diagnostics & logging

• Archive failing log stages, and collect an additional log file.
• Improve run-time reporting when a command times out, and avoid exiting the
  timeout sleep early on a signal.
• Move testrun directories aside rather than deleting them, to aid later
  diagnosis.

Bug fixes

• Defer module checkout until after find_changed, so PatchStack commits do
  not make find_changed always report a build is needed.
• Fix TAP-test duplication in configure/make builds (notably pg_plan_advice
  rerunning the whole regression suite), plus a scalar(glob()) Perl bug.
• Disable git system settings when looking for changed files.
• Fix finding the config file in the current directory in the auxiliary scripts.
• Use proxy settings, if any, in run_branches.pl.
• Skip the test_escape test on MSVC with old toolsets (non-meson, pre-16/17
  only).

Housekeeping

• Clean up old tmpdir objects and stale port-lock (.rsv) files.
• Avoid moving the .git directory when possible.
• Set $devnull in a principled way.
• Adjust for the unified Redis-FDW branches.

Downloads

the Release can be downloaded from https://buildfarm.postgresql.org/downloads/latest-client.tgz or https://github.com/PGBuildFarm/client-code/releases/tag/REL_21