use `env` in shebangs

[Boris Bobrov]

bash shebangs be changed to go to #!/usr/bin/env bash instead of /usr/bin/bash. That would make things work out of the box on systems where bash is not in /usr/bin, which is the case in all the BSDs and Solaris

[Loic Dachary]

Proposed fix ​http://workbench.dachary.org/dachary/mediagoblin/commit/ef8f98b9c16e2267c882c7f0d8580a4afcf6d371

[Sebastian Hugentobler]

would also fix #5312

[Christopher Allan Webber]

Good call. Merged and pushed, thank you!

[Christopher Allan Webber]

Ah.... so I merged this, and just today, I reverted it!

We have a problem: not using env makes things hard for bsd; using env makes things a non-starter for Guix.

[Christopher Allan Webber]

We might be able to have autotools make the distinction for us. I'll look into it.

[Christopher Allan Webber]

Wait a minute, /bin/sh still exists on *bsd systems right? It's just not bash!

We could rewrite our scripts to be more generic-bourne-style (or worst comes to worst, use m4sh) and then still use #!/bin/sh in general as our shebang.... right?

[Christopher Allan Webber]

So previously we were doing #!/usr/bin/bash. We're now doing #!/bin/sh, which is already more generic. Theoretically all posix-y systems should ship with a bourne-compatible /bin/sh, is my understanding.

So, instead people should raise specific bugs if our scripts use bash-specific features. We can then either generic'ify them, or in more difficult cases, use m4sh.

I think with that, it's fine to close this bug.