[grilo] Revert "core: Allow removing metadata keys in GrlData"

[Bastien Nocera <hadess src gnome org>]

commit e0e30dfa0ea5d9e4814b2cdb1236abfa74289076
Author: Bastien Nocera <hadess hadess net>
Date:   Thu Dec 11 00:34:49 2014 +0100

    Revert "core: Allow removing metadata keys in GrlData"
    
    This reverts commit 32275f8daace57eaea1899ad534244091e05e0a9.
    
    This patch broke adding empty strings as related keys, as the
    lastfm-albumart plugin tests showed.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=741207

 src/data/grl-data.c         |    6 ++++--
 src/data/grl-related-keys.c |   12 +++++-------
 2 files changed, 9 insertions(+), 9 deletions(-)
---
diff --git a/src/data/grl-data.c b/src/data/grl-data.c
index 9f9aba2..b453694 100644
--- a/src/data/grl-data.c
+++ b/src/data/grl-data.c
@@ -194,6 +194,10 @@ grl_data_set (GrlData *data, GrlKeyID key, const GValue *value)
   g_return_if_fail (GRL_IS_DATA (data));
   g_return_if_fail (key);
 
+  if (!value) {
+    return;
+  }
+
   /* Get the right set of related keys */
   if (grl_data_length (data, key) > 0) {
     relkeys = grl_data_get_related_keys (data, key, 0);
@@ -236,8 +240,6 @@ grl_data_set_string (GrlData *data,
     g_value_set_string (&value, strvalue);
     grl_data_set (data, key, &value);
     g_value_unset (&value);
-  } else {
-    grl_data_set (data, key, NULL);
   }
 }
 
diff --git a/src/data/grl-related-keys.c b/src/data/grl-related-keys.c
index feb0a7f..2bde3c0 100644
--- a/src/data/grl-related-keys.c
+++ b/src/data/grl-related-keys.c
@@ -242,20 +242,18 @@ grl_related_keys_set (GrlRelatedKeys *relkeys,
   g_return_if_fail (GRL_IS_RELATED_KEYS (relkeys));
   g_return_if_fail (key);
 
+  if (!value) {
+    return;
+  }
+
   /* Dup value */
-  if (value != NULL &&
-      G_VALUE_TYPE (value) != GRL_METADATA_KEY_GET_TYPE (key)) {
+  if (G_VALUE_TYPE (value) != GRL_METADATA_KEY_GET_TYPE (key)) {
     GRL_WARNING ("value has type %s, but expected %s",
                  g_type_name (G_VALUE_TYPE (value)),
                  g_type_name (GRL_METADATA_KEY_GET_TYPE (key)));
     return;
   }
 
-  if (!value) {
-    g_hash_table_remove (relkeys->priv->data, GRLKEYID_TO_POINTER (key));
-    return;
-  }
-
   copy = g_new0 (GValue, 1);
   g_value_init (copy, G_VALUE_TYPE (value));
   g_value_copy (value, copy);