configitems: add a new config option to control new filenode functionality
This series is adding functionality where we can force create a new filenode for
some files on a merge-commit. This is meant to represent an explicit choice made
by user and hence distingusing the file in the merged commit with the file in
parent by creating a new filenode instead of using the parent one.
This introduces a experimental config option under which this functionality
will be hidden.
A new testcase is added in tests/test-merge-criss-cross.t to test the new
functionality while making the option does not break other scenarios.
Differential Revision: https://phab.mercurial-scm.org/D9026
$ hg init
$ echo 123 > a
$ hg add a
$ hg commit -m "first" a
$ mkdir sub
$ echo 321 > sub/b
$ hg add sub/b
$ hg commit -m "second" sub/b
$ cat sub/b
321
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cat sub/b 2>/dev/null || echo "sub/b not present"
sub/b not present
$ test -d sub || echo "sub not present"
sub not present