We just added `rust-version = ` to the `secp256k1-sys` manifest, doing
so causes a grep statement from the vendor script to match this line -
we don't want that.
Tighten up the grep statement by only matching on `version` at the start
of the line.
This rewrite:
* Fixes some shellcheck issues (bad quoting, use of | instead of ||
near the beginning of the file)
* Automatically computes the version prefix, depend directory, etc.,
and provides instructions to override this with env vars if the
user really wants to do this.
* Detects when it would be destructive and refuses to run unless
passed the -f flag, rather than prompting the user for a yes/no
* Adds the capability to use cp rather than git clone, which I need
to run this from within Nix.
* Whitelists CHANGELOG.md which shouldn't get substituted.
Tobin C. Harding
Davidson Souza
Andrew Poelstra
Steven Roose