nix-helpers: b1de9f8f0411dcee24c372fa90ce519ea693e911

     1: From: Chris Warburton
     2: Date: Mon, 09 Apr 2018 10:06:57 +0100
     3: State: new
     4: Subject: Add a fetchIpfs function
     5: Message-Id: <93b977b47fb8f5db-0-artemis@nixos>
     6: 
     7: Takes a hash. It should look for a /ipfs directory, if not found it
     8: should look for a localhost HTTP API and fall back to ipfs.io.
     9: 
    10: Find some well-known content that we can use as our check.
    11: 
    12: Note: we don't need to take an sha256 or anything, since IPFS is
    13: content-addressed.
    14: 
    15: See if we can make them fixed-output derivations.