Fix non-first uses of a module.

The implementation of useOp has not been updated correctly to accomodate the
fact that the namespaces are no longer modified in place.

This fixes #1212.

pkg/eval/builtin_special.go

@@ -307,12 +307,11 @@ func useFromFile(fm *Frame, spec, path string, r diag.Ranger) (*Ns, error) {
 
 // TODO: Make access to fm.Evaler.modules concurrency-safe.
 func evalModule(fm *Frame, key string, src parse.Source, r diag.Ranger) (*Ns, error) {
-	// Make an empty scope to evaluate the module in.
-	ns := new(Ns)
-	// Load the namespace before executing. This prevent circular use'es from
-	// resulting in an infinite recursion.
+	// Make an empty namespace before executing. This prevent circular use'es
+	// from resulting in an infinite recursion.
+	fm.Evaler.modules[key] = new(Ns)
+	ns, err := fm.Eval(src, r, new(Ns))
 	fm.Evaler.modules[key] = ns
-	ns, err := fm.Eval(src, r, ns)
 	if err != nil {
 		// Unload the namespace.
 		delete(fm.Evaler.modules, key)

pkg/eval/builtin_special_test.go

@@ -152,6 +152,9 @@ func TestUse(t *testing.T) {
 		That(`use a/b/c/d; put $d:name`).Puts("a/b/c/d"),
 		// module is cached after first use
 		That(`use has-init; use has-init`).Puts("has-init"),
+		// repeated uses result in the same namespace being imported
+		That("use lorem; use lorem lorem2; put $lorem:name $lorem2:name").
+			Puts("lorem", "lorem"),
 		// overriding module
 		That(`use d; put $d:name; use a/b/c/d; put $d:name`).
 			Puts("d", "a/b/c/d"),