<!-- Please describe your changes on the following line: -->
The "$(some_command arg1 arg2)" form is preferred to the
`some_command arg1 arg2` form because it nests unambiguously.
Add a lint for this to tidy.
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).
<!-- Either: -->
- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
Source-Repo: https://github.com/servo/servo
Source-Revision: aa900b91aa9417b6aa032b4eff878f2916c480f0
<!-- Please describe your changes on the following line: -->
This changes tidy to check shell scripts for the proper shebang and
options. It does not check that variables are formatted correctly. It
also adds a check for the MPL 2.0 license in shell scripts.
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix#12158 (github issue number if applicable).
<!-- Either: -->
- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____
<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->
Source-Repo: https://github.com/servo/servo
Source-Revision: 4bc629b369242d16675161ab6af8141dab0bb556
