I looked for other examples in the code and found __lwp_thread_changepriority pretty damning, judge for yourself:

https://github.com/atgreen/RTEMS/blob/2f200c7e642c214accb7cc...

https://github.com/devkitPro/libogc/blob/52c525a13fd1762c103...

The only difference is that the prependit parameter and its associated branch is missing, other than that the functions are completely identical.