cmd/go: adjust import comment error

Fixes #7453.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/127210043

src/cmd/go/pkg.go

@@ -267,7 +267,7 @@ func loadImport(path string, srcDir string, stk *importStack, importPos []token.
 		bp.BinDir = gobin
 	}
 	if err == nil && !isLocal && bp.ImportComment != "" && bp.ImportComment != path {
-		err = fmt.Errorf("directory %s contains package %q", bp.Dir, bp.ImportComment)
+		err = fmt.Errorf("code in directory %s expects import %q", bp.Dir, bp.ImportComment)
 	}
 	p.load(stk, bp, err)
 	if p.Error != nil && len(importPos) > 0 {

src/cmd/go/test.bash

@@ -131,7 +131,7 @@ TEST 'import comment - mismatch'
 if ./testgo build ./testdata/importcom/wrongplace.go 2>testdata/err; then
 	echo 'go build ./testdata/importcom/wrongplace.go suceeded'
 	ok=false
-elif ! grep 'wrongplace contains package "my/x"' testdata/err >/dev/null; then
+elif ! grep 'wrongplace expects import "my/x"' testdata/err >/dev/null; then
 	echo 'go build did not mention incorrect import:'
 	cat testdata/err
 	ok=false