Users cannot import the TO API 4.0 client

[zrhoffman]

This Bug Report affects these Traffic Control components:

• Users and 3rd-party clients

Current behavior:

Go packages that are new in ATC 6.0.0 cannot be imported (unless you use a specific commit hash).

Related: #4380

Expected behavior:

Packages existing only in ATC 6.0.0 should be importable.

Steps to reproduce:

Try to get a package that only exists in ATC 6.0.0, not ATC 5.1.3:

[user@computer my-project]$ go mod init my-module
go: creating new go.mod: module my-module
[user@computer my-project]$ go get github.com/apache/trafficcontrol/traffic_ops/v4-client
go: module github.com/apache/trafficcontrol@upgrade found (v5.1.3+incompatible), but does not contain package github.com/apache/trafficcontrol/traffic_ops/v4-client

[zrhoffman]

To be clear on why I filed #6305 as a separate issue from #4380: Although the TO API client cannot be imported without specifying a commit hash, https://pkg.go.dev/github.com/apache/trafficcontrol/traffic_ops/v4-client shows up (although it is ec9ff6a, which is from the master branch).

[zrhoffman]

Fixed in #6305 (comment)

[zrhoffman]

This is still an issue