Before the change there was no way to poll for presence of
`vendorSha256` attribute:
$ nix-instantiate --strict --eval --expr 'with import ./. {}; _3mux.vendorSha256 or "no hash"'
error: attribute 'vendorSha256' missing
292| passthru = passthru // { inherit go goModules vendorHash; } // { inherit (args') vendorSha256; };
| ^
After the change the poll happens as expected:
$ nix-instantiate --strict --eval --expr 'with import ./. {}; _3mux.vendorSha256 or "no hash"'
"no hash"
a1422a7f8f