tests/test-status-inprocess.py.out

push: move bookmarks exchange in the exchange module

The bookmark exchange code was already extracted during a previous cycle. This
changesets moves the extracted function in this module. This function will read
and write data in the `pushoperation` object and It  is preferable to have all
core function collaborating through this object in the same place.

This changeset is pure code movement only. Code change for direct consumption of
the `pushoperation` object will come later.

% creating repo
% add and commit
C test.py
% change
M test.py