godeps using seemingly invalid commit hash

[Kyle Fazzari]

My CI has been failing for a while with a confusing error when building a godeps part:

Pulling mdns-publisher
+ snapcraftctl pull
Cloning into '/home/circleci/nextcloud-snap/parts/mdns-publisher/src'...
remote: Enumerating objects: 163, done.
remote: Total 163 (delta 0), reused 0 (delta 0), pack-reused 163
Receiving objects: 100% (163/163), 44.12 KiB | 2.10 MiB/s, done.
Resolving deltas: 100% (82/82), done.
Fetching godeps...
go get -d github.com/rogpeppe/godeps
go: downloading github.com/rogpeppe/godeps v0.0.0-20180524172459-404a7e748cd3
go: downloading github.com/kisielk/gotool v1.0.0
go: downloading github.com/pelletier/go-toml v1.8.1
go: downloading golang.org/x/tools v0.1.0
go: downloading golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4
git checkout 4e9e0ee19b60b13eb79915933f44d8ed5f268bdd
fatal: reference is not a tree: 4e9e0ee19b60b13eb79915933f44d8ed5f268bdd
Failed to run 'git checkout 4e9e0ee19b60b13eb79915933f44d8ed5f268bdd' for 'mdns-publisher': Exited with code 128.
Verify that the part is using the correct parameters and try again.

Exited with code exit status 2

Huh. That commit isn't anywhere in my project or my dependencies. Turns out it's actually in the godeps plugin itself, when it's trying to checkout go-toml:

    https://github.com/snapcore/snapcraft/blob/a6dfe1cd2c0457ea48940cbec84762e91bce4edb/snapcraft/plugins/v1/godeps.py#L134

It looks like that commit hash may no longer exist. This seems like a rather fragile way to do things, but we must have done it for a reason I don't understand. Is it something we can improve upon?

[Chris Patterson (cjp256)]

Hey Kyle, can you try pinning the go-channel to 1.15/stable (or earlier)? IIRC go get's behavior changed in 1.16 - and the plugin was updated to default to 1.15/stable.

[Kyle Fazzari (kyrofa)]

Hey Chris, spot on, that worked for my CI anyway. Looks like Launchpad was fixed with https://github.com/snapcore/snapcraft/pull/3475 .