evolve: extract logic to new method _evolvemerge This patch introduces a new method _evolvemerge to merge orig to dest in relocate method. This simplifies the code of the method relocate and allows us to re-use it later in the scope of the rework of 'hg evolve --continue'

syntax: re
/figures/[^/]+\.png$
^docs/build/
^docs/html/
^html/
\.pyc$
~$
\.swp$
\.orig$
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^tests/easy_run.sh$
^build/
^MANIFEST$
^docs/tutorials/.*\.rst$
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