John "codefu" McDole 7da78cb7b8
fix: get content hash for master on local engine branches (third attempt) (#173169)
The content hash doesn't exist for local engine changes, except for on
CI. If we detect we're on a branch with committed or uncommitted changes
to engine files; use "master".

towards #171790

re-land attempt for #173114 (try 2)
re-land attempt for #172792 (original)

The first commit in this PR is the previously LGTM'd changes for the
above; with tests.

The second commit is the critical change to make this work in post
submits (fixes #173143). It turns out that while LUCI reports the GitHub
private branches; our recipes directly checkout the git sha. This
matters because the content scripts couldn't determine the branch name
and the rev-parse was just HEAD. This lead the scripts down the
merge-base logic, which returns the previous commit.

A test was added specifically for this.

Alternatively to this change, we could have checked for LUCI_CONTEXT
being present in the environment. This is checked by Flutter tools in
some cases, but not by any other scripts in `bin/internal`. The downside
to checking HEAD: if you have a local branch with engine changes and you
move back a revision - `dart`/`flutter` invocations will generate the
hash for your local changes and fail.
2025-08-04 00:05:59 +00:00
..