cmd/go: fix error message when missing import

Fixes #48907

Change-Id: I504f846fc2ea655ba00aedb30f90847f938c347c
Reviewed-on: https://go-review.googlesource.com/c/go/+/360615
Run-TryBot: Ian Lance Taylor <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Trust: Emmanuel Odeke <[email protected]>

Author: zhouguangyuan0718

src/cmd/go/testdata/script/mod_go_version_missing.txt

@@ -27,7 +27,7 @@ cmp go.mod go.mod.orig
 
 ! go list -mod=vendor all
 ! stderr '^go: inconsistent vendoring'
-stderr 'cannot find package "\." in:\n\t.*[/\\]vendor[/\\]example.com[/\\]badedit$'
+stderr 'cannot find package "vendor/example.com/badedit" in:\n\t.*[/\\]vendor[/\\]example.com[/\\]badedit$'
 
 # When we set -mod=mod, the go version should be updated immediately,
 # to the current version, converting the requirements from eager to lazy.

src/go/build/build.go

@@ -789,7 +789,7 @@ Found:
 		}
 
 		// package was not found
-		return p, fmt.Errorf("cannot find package %q in:\n\t%s", path, p.Dir)
+		return p, fmt.Errorf("cannot find package %q in:\n\t%s", p.ImportPath, p.Dir)
 	}
 
 	if mode&FindOnly != 0 {