git-filter-repo/t
Elijah Newren 1fa8c2c70b filter-repo: add --replace-refs option
This adds the ability to automatically add new replacement refs for each
rewritten commit (as well as delete or update replacement refs that
existed before the run).  This will allow users to use either new or old
commit hashes to reference commits locally, though old commit hashes
will need to be unabbreviated.  The only requirement for this to work,
is that the person who does the rewrite also needs to push the replace
refs up where other users can grab them, and users who want to use them
need to modify their fetch refspecs to grab the replace refs.

However, other tools external to git may not understand replace refs...

Tools like Gerrit and GitHub apparently do not yet natively understand
replace refs.  Trying to view "commits" by the replacement ref will
yield various forms of "Not Found" in each tool.  One has to instead try
to view it as a branch with an odd name (including "refs/replace/"), and
often branches are accessed via a different URL style than commits so it
becomes very non-obvious to users how to access the info associated with
an old commit hash.

  * In Gerrit, instead of being able to search on the sha1sum or use a
    pre-defined URL to search and auto-redirect to the appropriate code
    review with
      https://gerrit.SITE.COM/#/q/${OLD_SHA1SUM},n,z
    one instead has to have a special plugin and go to a URL like
      https://gerrit.SITE.COM/plugins/gitiles/ORG/REPO/+/refs/replace/${OLD_SHA1SUM}
    but then the user isn't shown the actual code review and will need
    to guess which link to click on to get to it (and it'll only be
    there if the user included a Change-Id in the commit message).
  * In GitHub, instead of being able to go to a URL like
      https://github.SITE.COM/ORG/REPO/commit/${OLD_SHA1SUM}
    one instead has to navigate based on branch using
      https://github.SITE.COM/ORG/REPO/tree/refs/replace/${OLD_SHA1SUM}
    but that will show a listing of commits instead of information about
    a specific commit; the user has to manually click on the first commit
    to get to the desired location.

For now, providing replace refs at least allows users to access
information locally using old IDs; perhaps in time as other external
tools will gain a better understanding of how to use replace refs, the
barrier to history rewrites will decrease enough that big projects that
really need it (e.g. those that have committed many sins by commiting
stupidly large useless binary blobs) can at least seriously contemplate
the undertaking.  History rewrites will always have some drawbacks and
pain associated with them, as they should, but when warranted it's nice
to have transition plans that are more smooth than a massive flag day.

Signed-off-by: Elijah Newren <newren@gmail.com>
2019-05-11 13:24:00 -07:00
..
t9390 filter-repo: allow users to adjust pruning of empty & degenerate commits 2019-05-11 13:01:19 -07:00
t9391 filter-repo (python3): replace strings with bytestrings 2019-05-08 08:57:51 -07:00
run_coverage filter-repo (python3): convert run_coverage 2019-05-08 08:57:51 -07:00
t9390-filter-repo.sh filter-repo: add --replace-refs option 2019-05-11 13:24:00 -07:00
t9391-filter-repo-lib-usage.sh filter-repo (python3): shebang and imports 2019-05-08 08:57:51 -07:00
t9392-python-callback.sh filter-repo (python3): replace strings with bytestrings 2019-05-08 08:57:51 -07:00
test-lib-functions.sh filter-repo: add some basic tests, with git-style test-lib.sh 2019-03-12 14:19:38 -07:00
test-lib.sh filter-repo: add some basic tests, with git-style test-lib.sh 2019-03-12 14:19:38 -07:00