topics: add t0 and b0 to the stack
t0 or b0 will be the base of the stack and it's the parent of t1 or b1. The cool
thing about this is that if you update to t0 using `hg up t0` or do `hg prev` on
t1, you will be updated to t0 with the current topic preserved.
This patch adds t0 to stack and implement the preserving topic case for t0 while
using `hg update`.
[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