cmd/go/internal/work: properly ignore error

Change-Id: Id0e8d170730d946b60c661d90bc98d0ca7545391
GitHub-Last-Rev: 19fed775b7e87c8c721b4487458354a2d5532a6c
GitHub-Pull-Request: golang/go#30001
Reviewed-on: https://go-review.googlesource.com/c/160425Reviewed-by: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -268,7 +268,7 @@ func (b *Builder) buildActionID(a *Action) cache.ActionID {
 		fmt.Fprintf(h, "compile %s %q %q\n", id, forcedGccgoflags, p.Internal.Gccgoflags)
 		fmt.Fprintf(h, "pkgpath %s\n", gccgoPkgpath(p))
 		if len(p.SFiles) > 0 {
-			id, err = b.gccgoToolID(BuildToolchain.compiler(), "assembler-with-cpp")
+			id, _ = b.gccgoToolID(BuildToolchain.compiler(), "assembler-with-cpp")
 			// Ignore error; different assembler versions
 			// are unlikely to make any difference anyhow.
 			fmt.Fprintf(h, "asm %q\n", id)