Replace #!/bin/sh with #!/bin/bash

[vi]

Should resolve #47.

[sanmai-NL]

I strongly prefer to rewrite in portable shell code instead, or to not use a shell script at all for this (given the relative complexity of the script). How is rustup going to work satisfactorily on various platforms otherwise?

[vi]

rustup.sh may be obsoleted in favour of rustup.rs, so serious rewrite may be in vain.

[sanmai-NL]

The script is not that non-portable at present at all. See e.g. this comment

Revised: if rustup.rs is a suitable replacement (soon) anyway, briefly depending on /bin/bash is better than the current situation anyway.

[sanmai-NL]

@vi: I must have missed the announcement of the alternative tool in this repo? I hope this can be clarified so that you get to see a warning immediately when browsing this repo.

[vi]

@sanmai-NL, Main rustup.rs discussion thread is here: https://internals.rust-lang.org/t/beta-testing-rustup-rs/3316/83

[brson]

Sorry I've been ignoring this repo. From the linked issue, none of the bashisms seem fundamental. I'd rather just fix them. This script is likely to stick around for at least a few more months.