remove read-only restriction on /checkout

[onur-ozkan]

Currently, we are setting read-only restrictions on /checkout path in containers, which conflicts with various bootstrap linking logic. This change removes this restriction.

For more context, see #122709 (comment) and #127151

[rustbot]

r? @Mark-Simulacrum

rustbot has assigned @Mark-Simulacrum.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[onur-ozkan]

I am not sure how adding read-only restriction helps in containers. What is the reason behind it?

cc @rust-lang/infra

[bjorn3]

The source directory should never be modified during a build. Only the build directory may be modified. I'm pretty sure several distros enforce this.

[onur-ozkan]

The source directory should never be modified during a build. Only the build directory may be modified. I'm pretty sure several distros enforce this.

True.. I will check again and make sure not to copy things to /checkout when it is symlinked as this modifies the source directory.

[Kobzol]

It would be good to add this justification to the bash script.

[onur-ozkan]

Hopefully #127188 should fix the problem.