Always provide revision-related headers for Mercurial diffs.

Review Request #11151 — Created Aug. 31, 2020 and submitted

Information

RBTools
release-2.0.x

Reviewers

Git-style Mercurial diffs lack any useful information for specifying the
revisions of files. This meant that Review Board couldn't normally
extract any useful identifying information for any file fetches. We had
worked around this in the past by utilizing the diff upload API's
base_commit_id field, but that still meant that some information was
missing.

This triggered a breakage whenever a change consisted of a moved file.
Since the revision information wasn't available, the original file
couldn't be fetched correctly, since the base_commit_id wasn't enough
to help look it up.

Fortunately, Review Board does include support for extracting special
Mercurial headers containing this information. Those are only natively
generated in an hg export (see
https://bz.mercurial-scm.org/show_bug.cgi?id=6400), but adding this to
RBTools-generated Mercurial diffs is trivial.

This change implements these headers when generating diffs. We now
always generate a Git-style diff (which was effectively the behavior
for any modern version of Review Board anyway) and prepend these headers
to it.

All diff-related unit tests have been rewritten to carefully ensure that
we're generating these diffs correctly and that they have the exact
output we expect.

Unit tests passed.

Verified that generated diffs contained revision information and that
Review Board successfully used that to locate files, even when modifying
changes moved in a parent diff.

Summary ID
Always provide revision-related headers for Mercurial diffs.
Git-style Mercurial diffs lack any useful information for specifying the revisions of files. This meant that Review Board couldn't normally extract any useful identifying information for any file fetches. We had worked around this in the past by utilizing the diff upload API's `base_commit_id` field, but that still meant that some information was missing. This triggered a breakage whenever a change consisted of a moved file. Since the revision information wasn't available, the original file couldn't be fetched correctly, since the `base_commit_id` wasn't enough to help look it up. Fortunately, Review Board does include support for extracting special Mercurial headers containing this information. Those are only natively generated in an `hg export` (see https://bz.mercurial-scm.org/show_bug.cgi?id=6400), but adding this to RBTools-generated Mercurial diffs is trivial. This change implements these headers when generating diffs. We now *always* generate a Git-style diff (which was effectively the behavior for any modern version of Review Board anyway) and prepend these headers to it. All diff-related unit tests have been rewritten to carefully ensure that we're generating these diffs correctly and that they have the exact output we expect.
b2ae7d96d368b2dd4ae02a3ea464491832a5978d
Description From Last Updated

F841 local variable 'commit_id1' is assigned to but never used

reviewbotreviewbot

F841 local variable 'commit_id1' is assigned to but never used

reviewbotreviewbot
Checks run (1 failed, 1 succeeded)
flake8 failed.
JSHint passed.

flake8

chipx86
misery
  1. 
      
  2. Tested with my script... it works! Thanks!

  3. 
      
david
  1. Ship It!
  2. 
      
chipx86
Review request changed

Status: Closed (submitted)

Change Summary:

Pushed to master (497cf1c)
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