b4 doesn't notice updated base-commit

b4 doesn't notice updated base-commit

[Josh Steadmon]

Hi, just noticed this minor bug in b4 v0.8.0: when fetching the latest
version of a series, b4 seems to always advise that the base-commit is
whatever was advertised in the first cover letter, even if the
base-commit changes for later versions of the series. An example (from
the Git list):

```
$ b4 am -o - pull.1161.v4.git.1647843442911.gitgitgadget@gmail.com | git am
Looking up https://lore.kernel.org/r/pull.1161.v4.git.1647843442911.gitgitgadget%40gmail.com
[...]
 Base: dab1b7905d0b295f1acef9785bb2b9cbb0fdec84
       git checkout -b v4_20220228_gitgitgadget_gmail_com dab1b7905d0b295f1acef9785bb2b9cbb0fdec84
```

However, v4 of that series doesn't apply cleanly on dab1b79, and if we
check the actual v4 message we see that it has a new base-commit of
74cc1aa55f30ed76424a0e7226ab519aa6265061.


Thanks,
Josh

Re: b4 doesn't notice updated base-commit

[Kyle Meyer]

Josh Steadmon writes:

> Hi, just noticed this minor bug in b4 v0.8.0: when fetching the latest
> version of a series, b4 seems to always advise that the base-commit is
> whatever was advertised in the first cover letter, even if the
> base-commit changes for later versions of the series. An example (from
> the Git list):
>
> ```
> $ b4 am -o - pull.1161.v4.git.1647843442911.gitgitgadget@gmail.com | git am
> Looking up https://lore.kernel.org/r/pull.1161.v4.git.1647843442911.gitgitgadget%40gmail.com
> [...]
>  Base: dab1b7905d0b295f1acef9785bb2b9cbb0fdec84
>        git checkout -b v4_20220228_gitgitgadget_gmail_com dab1b7905d0b295f1acef9785bb2b9cbb0fdec84
> ```

I can trigger the issue on my end too, but I suspect it's more specific
than "always [advising] that the base-commit is whatever was advertised
in the first cover letter".

For example, here's a thread that has a different base commit at v1 and
the latest version (v10), and the correct base is picked up
(b80121027d12 not 5d01301f2b86):

  https://lore.kernel.org/git/pull.1212.git.git.1643915286.gitgitgadget@gmail.com/

Perhaps the problem with the thread you referenced has something to do
with v4 consisting of only one patch and no cover letter while the
previous iterations had multiple patches and a cover letter.

The cover letter written by 'b4 am' suggests it's getting stuck on the
cover letter for the v3:

  $ b4 am pull.1161.v4.git.1647843442911.gitgitgadget@gmail.com
  $ ls -1
  v4_20220228_gitgitgadget_adding_new_branch_autosetupmerge_option_simple.cover
  v4_20220228_gitgitgadget_adding_new_branch_autosetupmerge_option_simple.mbx
  $ grep Subject v4_20220228_gitgitgadget_adding_new_branch_autosetupmerge_option_simple.cover
  Subject: [PATCH v3 0/2] adding new branch.autosetupmerge option "simple"