Refactoring (membersManager package introduced) to make PY-3450 Refactoring: pull up class variables/attributes easier
Infer 'Iterable' as the type of tuples as default parameter values (PY-10967)

It is too strict to infer 'tuple' as the type of default tuples, since
they are often used as an immutable indicator, that a method expects a
collection.
[git] Don't read default commit message from .COMMIT_EDITMSG

This actually reverts 07af6c9fa (apart from code style changes).
It fixes IDEA-119753 and adding a newline after successful commit.

The root cause is actually CommitChangeListDialog#setComment
where the VCS CheckinEnvironment is asked even if we have some commit
message in history, which is then overwritten by the message received
from the VCS.
It seems more logical to ask VCS _only_ if we have nothing to propose,
but on the other hand, in such situations as merging it is very handy
to use a pre-populated message from VCS, rather than the previous
commit message as IDEA proposes.
Implementing some sort of commit message provider priority seems to
be an overhead for all of this => reverting commit which caused
commit message to be read from the VCS more often looks like a better
decision.
Fixed potential NPE
Merge branch 'python-fixes'
PY-3450 Refactoring: pull up class variables/attributes: Fixed, but refactoring is required.
Merge remote-tracking branch 'origin/master'