revsetlang: check number of arguments passed to formatspec()

revsetlang: catch invalid format character with %l prefix listexp() could call argtype() with an invalid format character, but that wasn't checked before.

py3: add 8 new passing tests to the whitelist Differential Revision: https://phab.mercurial-scm.org/D1800

py3: use list() to get a list of items using dict.items() dict.items() on Python 3 returns a generator over the values of the dictionary, hence we can't delete elements while iterating over dict.items() in Python 3. Differential Revision: https://phab.mercurial-scm.org/D1799

py3: convert dict keys' to str before passing as kwargs We have pycompat.strkwargs() which converts the keys of a dict to str and returns that. Differential Revision: https://phab.mercurial-scm.org/D1798

py3: make sure we open the file to write in bytes mode Differential Revision: https://phab.mercurial-scm.org/D1797

py3: don't use dict.iterkeys() Instead of iterating of dict.iterkeys(), let's iterate of dict as that will be equivalent and dict.iterkeys() is not present in Python 3. Differential Revision: https://phab.mercurial-scm.org/D1796

py3: use pycompat.bytestr() instead of str() Differential Revision: https://phab.mercurial-scm.org/D1795

py3: make regular expressions bytes by prepending b'' Regexes start with r'' and hence transformer skips adding b'' there. # skip-blame because we are just adding b'' Differential Revision: https://phab.mercurial-scm.org/D1794

py3: slice on bytes instead of indexing Indexing returns the ascii value on Python 3. Differential Revision: https://phab.mercurial-scm.org/D1793