Bug#850967: Clarify /usr/bin/foo should not be hardcoded even in upstream parts

[Sam Hartman <hartmans@debian.org>]

>>>>> "Josh" == Josh Triplett <josh@joshtriplett.org> writes:

    Josh> As another technical alternative, which I haven't seen
    Josh> mentioned elsewhere in this thread or related bug reports:
    Josh> when I need to override a packaged binary or file temporarily
    Josh> for debugging purposes, without forgetting to restore it
    Josh> later, I tend to use "mount --bind /my/replacement
    Josh> /usr/bin/foo".  For instance, for local testing while
    Josh> developing dh-cargo, which required a newer version of Cargo
    Josh> than packaged in Debian at the time, I built a local version
    Josh> of Cargo and did "mount --bind ~/src/cargo/target/debug/cargo
    Josh> /usr/bin/cargo".  That allowed me to easily test-build
    Josh> packages before the availability of a Debian package of a
    Josh> sufficiently new Cargo.

O, cool, that's really need.

And as a throw-back to an alternate Plan9 history, you could presumably
unshare your mount namespace and even do that for a subset of the
processes on a system, getting almost all the benefits of PATH.