view CONTRIBUTING @ 34085:e8a7c1a0565a

cmdutil: remove the redundant commit during amend

There was an extra commit made during the amend operation to track the
changes to the working copy. However, this logic was written a long time back
and newer API's make this extra commit redundant. Therefore, I am removing the
extra commit. After this change, I noticed that

  - Execution time of the cmdutil.amend improved by over 40%.
  - Execution time of "hg commit --amend" improved by over 20%.

Test Plan:
I ensured that the all the hg tests passed after the change. I had
to fix a few tests which were aware of the extra commit made during the amend.

Differential Revision: https://phab.mercurial-scm.org/D636

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