tests/test-check-format.t

copies: add a HASCOPIESINFO flag to highlight rev with useful data

If some files changes that may impact copy tracing are detected, we set this
flag. This helps the copy tracing algorithm to skip fetching possibly expensive
data when unnecessary.

Differential Revision: https://phab.mercurial-scm.org/D9139

#require black test-repo

  $ cd $RUNTESTDIR/..
  $ black --config=black.toml --check --diff `hg files 'set:(**.py + grep("^#!.*python")) - mercurial/thirdparty/**'`