re2: make errors quiet
By default, the re2 library will output error on its own instead of keeping the
error in an exception. This make re2 printing spurious error before fallback to
the stdlib remodule that may accept the pattern or also fails to parse it and
raise a proper error that will be handled by Mercurial.
So we also pass an Option object that changes this default.
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273ce12ad8f1` will report some style violations on a very old commit).