fold: reword error message for public commits
This rewords the error message when attempting to fold public csets.
It is somewhat clearer to not use contractions in formal writing. It
also uses i18n for it. This commit also adds a new test for this error
message.
recursive-include docs/figures *.svg
include docs/figures/hgview-example.png
include docs/*.rst
include docs/*.py
include docs/tutorials/*.t
include docs/makefile
include docs/static/*.svg
include hgext/__init__.py
include hgext/evolve.py
include hgext/pushexperiment.py
include setup.py
include README
include COPYING
include tests/*.t
include tests/*.py
exclude tests/test-oldconvert.t
exclude tests/test-qsync.t