tests/test-custom-filters.out

dirstate: refactor granularity code, add a test

- rename option dirstate.granularity
- move option reading into .write()
- add a simple test

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Some stuff to ponder very carefully.
% Fresh checkout:
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Copyright 2046, The Masters
Some stuff to ponder very carefully.
M stuff.txt
% Problem encoding:
abort: missing header "Copyright 2046, The Masters" in morestuff.txt
M stuff.txt
A morestuff.txt