Reusing Bitcoin Core's Gitian dependency cache

[JeremyRand]

According to @luke-jr (via IRC conversation during the OpenSSL Consensus Bug response) we can reuse Bitcoin Core's Gitian dependency cache if we keep certain strings in the Gitian script the same as Bitcoin. I'm not 100% sure which strings need to be kept the same. Is it just the name at https://github.com/namecoin/namecoin-core/blob/master/contrib/gitian-descriptors/gitian-linux.yml#L2 ?

[josephbisch]

Looks like it is just the name: https://github.com/devrandom/gitian-builder/blob/923016ec8d1abb127c92a127a527f71c67d78acf/bin/gbuild#L83.

[JeremyRand]

I changed the name to use "bitcoin" instead of "namecoin". This did make Gitian reuse the dependency cache, but the build failed (seemed to have trouble finding a Qt header). I'll come back to this later, but for now I think we'll avoid making this change.

[domob1812]

@JeremyRand, is this still relevant (and if so, do you plan to work on this)?

[JeremyRand]

It's probably still relevant, and it would be great if someone wants to experiment with this, but I'm not likely to have time to touch this in the next couple months.