revset: factor out composing error message for ParseError to reuse...
revset: factor out composing error message for ParseError to reuse
This patch defines the composing function not in "ParseError" class but
in "revset" module, because:
- "_()" shouldn't be used in "ParseError", to avoid adding "from
i18n import _" i18n" to "error" module
- generalizing message composition of"ParseError" for all code paths
other than revset isn't the purpose of this patch
we should also take care of showing "unexpected leading
whitespace" for some code paths, to generalize widely.