Auto merge of #26720 - camelid:real-version-hash, r=SimonSapin

Show the real commit hash for `./servo --version`, not the bundle hash

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Show the real commit hash of the build when run on a bundle commit, rather than showing the bundle's hash.

It gets the real commit hash by extracting it from the bundle commit message, which has the form `Shallow version of commit {sha1}`, where `{sha1}` is the real commit hash.

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- [x] `./mach build -d` does not report any errors (edits Python code, no Rust changes)
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #26386 (GitHub issue number if applicable)

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because this only changes infrastructure

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0 files changed, 0 insertions, 0 deletions