view .arcconfig @ 42426:602469a91550

context: get filesadded() and filesremoved() from changeset if configured

This adds the read side for getting the sets of added and removed
files from the changeset extras. I timed this command on the hg repo:

  hg log -T '{rev}\n {files}\n %:{file_mods}\n +{file_adds}\n -{file_dels}\n'

It took 1m21s before and 6.4s after. I also used that command to check
that the result didn't change compared to calculating the values from
the manifests on the fly (it didn't change).

In the mozilla-unified repo, the same command run on
FIREFOX_BETA_58_END::FIREFOX_BETA_59_END went from 29s to 0.67s.

Differential Revision: https://phab.mercurial-scm.org/D6417

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    "base": "hg:.^"
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