cargo fix hard-codes the bug report URL

[jyn514]

fix applies to more tools than just rustc itself; cargo clippy --fix is supported on stable, and I hope to make rustdoc lints fixable in the future: #13025

It would be nice to make this the correct url for each tool, either by making it configurable somehow or hard-coding a different URL per-tool.

after fixes were automatically applied the compiler reported errors within these files:

  * src/main.rs

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust/issues
quoting the full output of this command we'd be very appreciative!

Originally posted by @jyn514 in rust-lang/rust#109486 (comment)

[ehuss]

Transferred to rust-lang/cargo as this message is generated from cargo.

[Rustin170506]

@rustbot claim

I will try to improve it.

[weihanglo]

Note that although #11882 is a bit hacky (check if rustc workspace wrapper is clippy) and still hard-coded, it looks sufficient for today's needs. We could expand it more in the future if more tools come out.