cmd/dist, cmd/go: make GODEBUG=godebughash=1 ./make.bash work better

The change in cmd/dist ignores debug output, instead of assuming
any output is from the template.

The change in cmd/go makes the debug output show the package name
on every line, so that interlaced prints can be deinterlaced.

Change-Id: Ic3d59ee0256271067cb9be2fde643a0e19405375
Reviewed-on: https://go-review.googlesource.com/76019
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

src/cmd/dist/build.go

@@ -1309,12 +1309,12 @@ func checkNotStale(goBinary string, targets ...string) {
 		append([]string{
 			goBinary,
 			"list", "-gcflags=" + gogcflags, "-ldflags=" + goldflags,
-			"-f={{if .Stale}}\t{{.ImportPath}}: {{.StaleReason}}{{end}}",
+			"-f={{if .Stale}}\tSTALE {{.ImportPath}}: {{.StaleReason}}{{end}}",
 		}, targets...)...)
-	if out != "" {
+	if strings.Contains(out, "\tSTALE ") {
 		os.Setenv("GODEBUG", "gocachehash=1")
 		for _, target := range []string{"runtime/internal/sys", "cmd/dist", "cmd/link"} {
-			if strings.Contains(out, target) {
+			if strings.Contains(out, "STALE "+target) {
 				run(goroot, ShowOutput|CheckExit, goBinary, "list", "-f={{.ImportPath}} {{.Stale}}", target)
 				break
 			}

src/cmd/go/internal/work/exec.go

@@ -168,8 +168,8 @@ func (b *Builder) Do(root *Action) {
 
 // buildActionID computes the action ID for a build action.
 func (b *Builder) buildActionID(a *Action) cache.ActionID {
-	h := cache.NewHash("actionID")
 	p := a.Package
+	h := cache.NewHash("build " + p.ImportPath)
 
 	// Configuration independent of compiler toolchain.
 	// Note: buildmode has already been accounted for in buildGcflags
@@ -667,8 +667,8 @@ func (b *Builder) vet(a *Action) error {
 
 // linkActionID computes the action ID for a link action.
 func (b *Builder) linkActionID(a *Action) cache.ActionID {
-	h := cache.NewHash("link")
 	p := a.Package
+	h := cache.NewHash("link " + p.ImportPath)
 
 	// Toolchain-independent configuration.
 	fmt.Fprintf(h, "link\n")