tests/test-check-rust-format.t

merge: make mergeresult constructor initialize empty object

In future patches, we will be going to update mergeresult object
instead of building an actions dict and then setting it in the object.

Differential Revision: https://phab.mercurial-scm.org/D8819

#require rustfmt test-repo

  $ . "$TESTDIR/helpers-testrepo.sh"

  $ cd "$TESTDIR"/..
  $ RUSTFMT=$(rustup which --toolchain nightly rustfmt)
  $ for f in `testrepohg files 'glob:**/*.rs'` ; do
  >   $RUSTFMT --check --edition=2018 --unstable-features --color=never $f
  > done