[Bug rust/117869] rust fails to build with cargo command error

[sjames at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117869

--- Comment #3 from Sam James <sjames at gcc dot gnu.org> ---
Since r15-9083-gd560f3f9594339, 1.49 should work again, but it needs
documenting still.