Remove unnecessary logic from Context.matchPackages

Updates #505

The fix for #505 in #555 was overly agressive, remove the unnecessary parts.

context.go

@@ -441,50 +441,40 @@ func matchPackages(c *Context, pattern string) ([]string, error) {
 
 	var pkgs []string
 
-	srcs := []string{
-		filepath.Join(c.Projectdir(), "src") + string(filepath.Separator),
-		filepath.Join(c.Projectdir(), "vendor", "src") + string(filepath.Separator),
-	}
-	for _, src := range srcs {
-		err := filepath.Walk(src, func(path string, fi os.FileInfo, err error) error {
-			if err != nil || !fi.IsDir() || path == src {
-				return nil
-			}
+	src := filepath.Join(c.Projectdir(), "src") + string(filepath.Separator)
+	err := filepath.Walk(src, func(path string, fi os.FileInfo, err error) error {
+		if err != nil || !fi.IsDir() || path == src {
+			return nil
+		}
 
-			// Avoid .foo, _foo, and testdata directory trees.
-			elem := fi.Name()
-			if strings.HasPrefix(elem, ".") || strings.HasPrefix(elem, "_") || elem == "testdata" {
-				return filepath.SkipDir
-			}
+		// Avoid .foo, _foo, and testdata directory trees.
+		elem := fi.Name()
+		if strings.HasPrefix(elem, ".") || strings.HasPrefix(elem, "_") || elem == "testdata" {
+			return filepath.SkipDir
+		}
 
-			name := filepath.ToSlash(path[len(src):])
-			if pattern == "std" && strings.Contains(name, ".") {
-				return filepath.SkipDir
-			}
-			if !treeCanMatch(name) {
-				return filepath.SkipDir
-			}
-			if !match(name) {
-				return nil
-			}
-			_, err = c.importers[1].Import(name)
-			switch err.(type) {
-			case nil:
-				pkgs = append(pkgs, name)
-				return nil
-			case *importer.NoGoError:
-				return nil // skip
-			case *os.PathError:
-				return nil // skip
-			default:
-				return err
-			}
-		})
-		if err != nil {
-			return nil, err
+		name := filepath.ToSlash(path[len(src):])
+		if pattern == "std" && strings.Contains(name, ".") {
+			return filepath.SkipDir
 		}
-	}
-	return pkgs, nil
+		if !treeCanMatch(name) {
+			return filepath.SkipDir
+		}
+		if !match(name) {
+			return nil
+		}
+		_, err = c.importers[1].Import(name)
+		switch err.(type) {
+		case nil:
+			pkgs = append(pkgs, name)
+			return nil
+		case *importer.NoGoError:
+			return nil // skip
+		default:
+			return err
+		}
+	})
+	return pkgs, err
 }
 
 // envForDir returns a copy of the environment