#require test-repo

  $ checkflake8() {

  >   if ! (which flake8 > /dev/null); then

  >     echo skipped: missing tool: flake8;

  >     exit 80;

  >   fi;

  > };

  $ checkflake8

Copied from Mercurial core (60ee2593a270)

  $ cd "`dirname "$TESTDIR"`"

run flake8 if it exists; if it doesn't, then just skip

  $ hg files -0 'set:(**.py or grep("^#!.*python")) - removed()' \

  > -X hgext3rd/evolve/thirdparty \

  > 2>/dev/null \

  > | xargs -0 flake8