tests/.balto.toml

convert: don't drop commits that are empty in the source when using --filemap

I ran into this when using `hg lfconvert --to-normal` (which uses the filemap
class internally), and saw that commits with nothing but a branch change were
dropped.  We could put in an option that only lfconvert uses internally.  But
silently dropping anything other than a commit where all changes were excluded
seems unintended.  For example, there's a message in mercurial_sink.putcommit()
if it drops an empty commit.  (And the reason that isn't kicking in here is
because lfconvert isn't passing --filemap, so the self.filemapmode conditional
there is always False.)

The naive change of `return not files` broke test-convert-filemap.t, so this is
a little more elaborate than needed for converting from largefiles.

# Balto (https://bitbucket.org/lothiraldan/balto/src) is a test orchestrator
# which is compatible with all test runner that can emit the LITF
# (https://github.com/lothiraldan/litf) test format.

# The plugin for the Mercurial test runner is mercurial-litf
# (https://pypi.org/project/mercurial-litf/). Make sure to follow the
# instruction and configuration instructions here:
# https://bitbucket.org/lothiraldan/mercurial_litf/src/default/

# You can launch Balto with `balto /path/to/mercurial/tests/`

name = "Mercurial Test Suite"
tool = "mercurial"