net/http: go 1.20.6 host validation breaks setting Host to a unix socket address [1.20 backport]

[gopherbot]

@neild requested issue #61431 to be considered for backport to the next 1.20 minor release.

@gopherbot please open backport issues. This is a regression.

[gopherbot]

Change https://go.dev/cl/518756 mentions this issue: [release-branch.go1.20] net/http: permit requests with invalid Host headers

[gopherbot]

Closed by merging ede3e27 to release-branch.go1.20.