Tags at the base of a stable branch get picked up twice

[Stephen Finucane]

Take the following git repo:

    * e12c6cf (HEAD -> master) Fix a bug on master
    * 37a0ae9 doc: Handle multiple branches in release notes
    | * 37adb10 (tag: 1.0.1, stable/1.0) Fix a bug on stable
    |/
    * af01c51 (tag: 1.0.0) Release 1.0
    * 0faba45 Integrate reno
    * a7beb14 (tag: 0.1.0) Add documentation
    * e23b0c8 Add gitignore
    * ff980c7 Initial commit

We've branched off _after_ the initial 1.0.0 release. Commit 'af01c51' contains a release note with a prelude for 1.0.0. This should only show up in the logs for the stable/1.0 branch. However, when you build docs, it shows up on both.

We should probably check if a commit exists in multiple places. If it does, go for the (oldest?) stable branch and drop it elsewhere.

[Stephen Finucane (stephenfinucane)]

Demonstration here: https://github.com/stephenfin/reno-bug-1748162

[Stephen Finucane (stephenfinucane)]

There's another variant available here: https://github.com/stephenfin/reno-bug-1748162-2

In this case, I'm seeing the initial reno added in '0faba45' being picked up for both branches.

    * ad13f52 (HEAD -> master, origin/master) Fix a bug on master
    * 81b6b41 doc: Handle multiple branches in release notes
    | * 9723350 (tag: 1.0.1, origin/stable/1.0, stable/1.0) Fix a bug on stable
    | * 49e2158 (tag: 1.0.0) Release 1.0
    |/
    * 0faba45 Integrate reno
    * a7beb14 (tag: 0.1.0) Add documentation
    * e23b0c8 Add gitignore
    * ff980c7 Initial commit

[Doug Hellmann (doug-hellmann)]

This is happening because the commit *is* on both branches and that commit isn't tagged so reno isn't recognizing it as the base of a branch. In OpenStack we always branch at a tag, but I guess that's not the case for the project you're looking at.

[Doug Hellmann (doug-hellmann)]

The bug tracker for reno has moved to storyboard: https://storyboard.openstack.org/#!/project/933