Fixed

• The error raised when a .jj/ directory is found but jj is not installed now names the environment variables that actually disable jj discovery (SETUPTOOLS_SCM_DISABLE_JJ=1 / VCS_VERSIONING_DISABLE_JJ=1) instead of an unprefixed DISABLE_JJ=1, which was never read. (#1537)

• The "unable to detect version" error now names the environment variables the
  running integration actually reads. It previously suggested
  SETUPTOOLS_SCM_PRETEND_VERSION_FOR_${NORMALIZED_DIST_NAME} unconditionally,
  which is not read by vcs-versioning on its own (or by any other integrator),
  and it named setuptools-scm as the failing tool regardless of which one ran.

  When the distribution name is known the suggested variable is spelled out in
  full. When it is not, the generic variables are suggested instead, with a note
  that the per-distribution ..._FOR_<DIST> form needs a dist name to match --
  the previous message offered a ${NORMALIZED_DIST_NAME} template that could
  never be filled in. (#1539)

• Warn when file discovery is suppressed while a VCS marker sits in the
  project directory. scm_search_known_failed() means an integrator already
  looked and found no checkout, so a .git, .hg or .jj right there
  contradicts it and the artifact is about to lose every tracked file. That
  combination was the signature of the pretend-version regression and stayed
  invisible for three releases. Parent directories are not searched, since an
  unpacked sdist inside an unrelated checkout is the case the suppression
  exists for, and roots listed in IGNORE_VCS_ROOTS are skipped. (#1540)

Miscellaneous

• Environment variable names are now built in one place (env_var_name /
  EnvReader.candidate_names), shared by the lookup in EnvReader.read and by
  every error message that suggests a variable, so a message cannot name a
  variable the lookup would not honour.

  The "repository found in a parent directory" error no longer offers a
  get_version(relative_to=...) call to integrators that do not ship one; the
  remaining options are renumbered instead. (#1539)