cmd/doc: go doc rsc.io/quote/v3 in module mode shows wrong import path

[rsc]

In module mode, in a module with rsc.io/quote/v3 as a dependency:

$ go doc rsc.io/quote/v3
package quote // import "rsc.io/quote"

Package quote collects pithy sayings.

func Concurrency() string
func GlassV3() string
func GoV3() string
func HelloV3() string
func OptV3() string
$ 

Note the import comment on the first line of output.
It should say rsc.io/quote/v3.
I do not know why it says rsc.io/quote instead.

[go101]

It looks the specified import path doesn't work when modules feature is enabled.

[agnivade]

/cc @robpike

[dmitshur]

I'll be able to look into this issue.

[dmitshur]

Actually, I can't reproduce this with Go 1.12.1 nor Go tip (at commit fd270d8):

$ cd $(mktemp -d)
$ go mod init m
go: creating new go.mod: module m
$ go get rsc.io/quote/v3
$ go doc rsc.io/quote/v3
package quote // import "rsc.io/quote/v3"

Package quote collects pithy sayings.

func Concurrency() string
func GlassV3() string
func GoV3() string
func HelloV3() string
func OptV3() string

@rsc What version of Go did you use? Where were the commands you ran before to initialize the main module?