Skip -i flag in go build if modules are enabled (#1337)

Using -i flag when running go build is not useful with go modules enabled
and in some cases can lead to a bug, with go trying to rebuild
shipped vendorized dependencies as described in this issue
golang/go#27285.
With this commit we check if go modules are enabled and we drop the -i
flag accordingly.

buffalo/cmd/build/bin.go

@@ -5,15 +5,20 @@ import (
 	"strings"
 
 	"github.com/gobuffalo/envy"
+	"github.com/gobuffalo/genny/movinglater/gotools/gomods"
 	"github.com/pkg/errors"
 )
 
 func (b *Builder) buildBin() error {
-	buildArgs := []string{"build", "-i"}
+	buildArgs := []string{"build"}
 	if b.Debug {
 		buildArgs = append(buildArgs, "-v")
 	}
 
+	if !gomods.On() {
+		buildArgs = append(buildArgs, "-i")
+	}
+
 	tf := b.App.BuildTags(b.Environment, b.Tags...)
 	buildArgs = append(buildArgs, "-tags", tf.String())