Prefer into_iter over drain

src/core/collection/artist.rs

@@ -72,10 +72,10 @@ impl Artist {
 
     fn merge_albums_by_lib_id(
         primary_albums: &mut [Album],
-        mut secondary_albums: Vec<Album>,
+        secondary_albums: Vec<Album>,
     ) -> HashMap<String, Vec<Album>> {
         let mut secondary_without_id = HashMap::<String, Vec<Album>>::new();
-        for secondary_album in secondary_albums.drain(..) {
+        for secondary_album in secondary_albums.into_iter() {
             let unmerged = Artist::merge_album_by_lib_id(primary_albums, secondary_album);
             if let Some(secondary_album) = unmerged {
                 secondary_without_id
@@ -89,9 +89,9 @@ impl Artist {
 
     fn merge_albums_by_title(
         primary_albums: &mut Vec<Album>,
-        mut secondary_without_id: HashMap<String, Vec<Album>>,
+        secondary_without_id: HashMap<String, Vec<Album>>,
     ) {
-        for (title, mut secondary_albums) in secondary_without_id.drain() {
+        for (title, mut secondary_albums) in secondary_without_id.into_iter() {
             let mut iter = primary_albums.iter_mut();
             match iter.find(|album| album.meta.id.title == title) {
                 Some(ref mut primary_album) => {

src/core/collection/merge.rs

@@ -23,8 +23,8 @@ impl<T: Ord> Merge for Vec<T> {
 }
 
 impl<K: Hash + PartialEq + Eq, T: Ord> Merge for HashMap<K, Vec<T>> {
-    fn merge_in_place(&mut self, mut other: Self) {
+    fn merge_in_place(&mut self, other: Self) {
-        for (other_key, other_value) in other.drain() {
+        for (other_key, other_value) in other.into_iter() {
             if let Some(ref mut value) = self.get_mut(&other_key) {
                 value.merge_in_place(other_value)
             } else {