This seems to have been caused by having the wrong PID. I don't know why
it worked before in the sandbox, but the code was definitely wrong
before, so let's just fix it.
Change-Id: I556580bdf614c716566310e975a36daa6d6c9a91
Fixes#183, #110, #116.
The default flake-registry option becomes 'vendored', and refers
to a vendored flake-registry.json file in the install path.
Vendored copy of the flake-registry is from github:NixOS/flake-registry
at commit 9c69f7bd2363e71fe5cd7f608113290c7614dcdd.
Change-Id: I752b81c85ebeaab4e582ac01c239d69d65580f37
