Fix panic when specifying multiple excludeFiles directives

Fixes #9076

hugolib/mount_filters_test.go

@@ -62,7 +62,7 @@ includeFiles = "/mydata/**"
 [[module.mounts]]
 source = 'assets'
 target = 'assets'
-excludeFiles = "/**exclude.*"
+excludeFiles = ["/**exclude.*", "/moooo.*"]
 [[module.mounts]]
 source = 'i18n'
 target = 'i18n'

modules/collect.go

@@ -149,13 +149,13 @@ func (m *ModulesConfig) finalize(logger loggers.Logger) error {
 
 func filterUnwantedMounts(mounts []Mount) []Mount {
 	// Remove duplicates
-	seen := make(map[Mount]bool)
+	seen := make(map[string]bool)
 	tmp := mounts[:0]
 	for _, m := range mounts {
-		if !seen[m] {
+		if !seen[m.key()] {
 			tmp = append(tmp, m)
 		}
-		seen[m] = true
+		seen[m.key()] = true
 	}
 	return tmp
 }

modules/config.go

@@ -15,6 +15,7 @@ package modules
 
 import (
 	"fmt"
+	"path"
 	"path/filepath"
 	"strings"
 
@@ -386,6 +387,11 @@ type Mount struct {
 	ExcludeFiles interface{}
 }
 
+// Used as key to remove duplicates.
+func (m Mount) key() string {
+	return path.Join(m.Lang, m.Source, m.Target)
+}
+
 func (m Mount) Component() string {
 	return strings.Split(m.Target, fileSeparator)[0]
 }