evolve: add comptability to read old evolvestate files
When a user runs `hg evolve` with old evolve where we used to write evolvestate
the old ways i.e. without using cbor, and faces conflicts, the evolve is
interrupted. If the user updates evolve before completing the evolve, that can
result in traceback as the new evolve cannot read the old evolvestate file.
The previous patch added function to read old evolvestate file and this patch
uses that when we encounter the above mentioned case.
[flake8]
ignore =
#closing bracket does not match indentation of opening bracket's line
E123,
# closing bracket does not match visual indentation
E124,
# visually indented line with same indent as next logical line
E129,
# at least two spaces before inline comment
E261,
# too many leading '#' for block comment
E266,
# expected 2 blank lines, found 0
E302,
# expected 2 blank lines after end of function or class
E305,
# module level import not at top of file
E402,
# line too long (82 > 79 characters)
E501,
# do not assign a lambda expression, use a def
E731,
# class names should use CapWords convention
N801,
# line break occurred before a binary operator
W503
builtins=xrange, execfile