Auto merge of #10483 - cuviper:vcs--, r=Eh2406
Auto merge of #10483 - cuviper:vcs--, r=Eh2406

Separate VCS command paths with "--"

When building a VCS command, there may be ambiguity if a relative path
looks like an option, like "-path" or "--path". All of the VCS commands
that we use support a bare "--" separator for non-option arguments,
which is good practice to apply here.

This does not affect the cargo CLI, as it already makes sure to use
absolute paths for these calls via `value_of_path()`.

rust-lang/cargo,rustyhorde/cargo,nipunn1313/cargo,eminence/cargo,rust-lang/cargo,eminence/cargo,nipunn1313/cargo,rustyhorde/cargo,eminence/cargo,nipunn1313/cargo,rust-lang/cargo,rustyhorde/cargo,rustyhorde/cargo,rust-lang/cargo,eminence/cargo,nipunn1313/cargo