Auto merge of #21833 - servo:jdm-patch-37, r=SimonSapin
Auto merge of #21833 - servo:jdm-patch-37, r=SimonSapin

Fix appveyor build

- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #21832
- [x] There are tests for these changes

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