Nightly builds of obfs4 are failing

Nightly builds of obfs4 fail with the following error:

Starting build: Sun Nov  4 02:09:59 2018
go: missing Git command. See https://golang.org/s/gogetcmd
go: missing Git command. See https://golang.org/s/gogetcmd
go: missing Git command. See https://golang.org/s/gogetcmd
go: git.torproject.org/pluggable-transports/goptlib.git@v0.0.0-20180321061416-7d56ec4f381e: git init --bare in /var/tmp/dist/gopath/pkg/mod/cache/vcs/a1643565e160bd0cf0e6283c6f3360d36ea15fa020f44619773cc82b775dfd2f: exec: "git": executable file not found in $PATH
go: github.com/agl/ed25519@v0.0.0-20170116200512-5312a6153412: git init --bare in /var/tmp/dist/gopath/pkg/mod/cache/vcs/0b82478dc41eb662b31914d0f711acabb12bf913cb746feb99c21463b792f537: exec: "git": executable file not found in $PATH
go: github.com/dchest/siphash@v1.2.0: git init --bare in /var/tmp/dist/gopath/pkg/mod/cache/vcs/7839629564df366d975b0413e853645690a1d25430b2a0077d2615a05e23ad7d: exec: "git": executable file not found in $PATH
go: golang.org/x/net@v0.0.0-20181011144130-49bb7cea24b1: unrecognized import path "golang.org/x/net" (https fetch: Get https://golang.org/x/net?go-get=1: x509: certificate signed by unknown authority)
go: golang.org/x/crypto@v0.0.0-20181015023909-0c41d7ab0a0e: unrecognized import path "golang.org/x/crypto" (https fetch: Get https://golang.org/x/crypto?go-get=1: x509: certificate signed by unknown authority)
go: error loading module requirements

This seems related to obfs4 commit 08f4d470188e9dad8658f2d2107880d8fdf326be: https://gitweb.torproject.org/pluggable-transports/obfs4.git/commit/?id=08f4d470188e9dad8658f2d2107880d8fdf326be