Comment 8 for bug 2007642

To conclude, how this happened but flew under the radar (both upstream and us):

- The author of that upstream change did not consider the possibility of breaking Linux distros like Debian (they stated in the PR that "this finds the sysroot using Rust driver DLLs."
- "Modern" Linux distros did not encounter this issue because they use non-multiarch layout.
- Some other Linux distros discovered the issue but stayed silent and worked around it using their own mechanisms.
- I did not discover this issue because the new Cargo 0.68 was built using Rust 1.66, and the test suite for Rust 1.67 did not include tests for testing directory look-up.

In the future, I will add a basic smoke test for Rust to prevent this kind of issue and catch the problem early.