This is allowed because since 2021-04-06 (when PR
https://github.com/galaxyproject/galaxy/pull/11777 was merged), our pull
request template contains a checkbox asking the contributor to allow the
Galaxy committers to license all their contributions to the core galaxy
codebase under the MIT license.
Explicit approval to this change will be sought from the few persons who:
- opened a PR before 2021-04-07 which was merged after this date, and
- haven't already agreed to the re-licensing in a later PR.
Nicola Soranzo