ensure BoneGroup names are kept unique.

source/blender/makesdna/DNA_action_types.h

@@ -341,7 +341,7 @@ typedef struct bPose {
 	void *ikparam;				/* IK solver parameters, structure depends on iksolver */ 
 	
 	bAnimVizSettings avs;		/* settings for visualisation of bone animation */
-	char proxy_act_bone[32];           /*proxy active bone name*/
+	char proxy_act_bone[32];    /* proxy active bone name*/
 } bPose;
 
 
@@ -423,6 +423,8 @@ typedef enum eItasc_Solver {
  * This is also exploited for bone-groups. Bone-Groups are stored per bPose, and are used 
  * primarily to color bones in the 3d-view. There are other benefits too, but those are mostly related
  * to Action-Groups.
+ *
+ * Note that these two uses each have their own RNA 'ActionGroup' and 'BoneGroup'.
  */
 typedef struct bActionGroup {
 	struct bActionGroup *next, *prev;

source/blender/makesrna/intern/rna_pose.c

@@ -139,6 +139,17 @@ static void rna_BoneGroup_color_set_set(PointerRNA *ptr, int value)
 	}
 }
 
+void rna_BoneGroup_name_set(PointerRNA *ptr, const char *value)
+{
+	Object *ob= ptr->id.data;
+	bActionGroup *agrp= ptr->data;
+
+	/* copy the new name into the name slot */
+	BLI_strncpy_utf8(agrp->name, value, sizeof(agrp->name));
+
+	BLI_uniquename(&ob->pose->agroups, agrp, "Group", '.', offsetof(bActionGroup, name), sizeof(agrp->name));
+}
+
 static IDProperty *rna_PoseBone_idprops(PointerRNA *ptr, int create)
 {
 	bPoseChannel *pchan= ptr->data;
@@ -657,6 +668,7 @@ static void rna_def_bone_group(BlenderRNA *brna)
 	/* name */
 	prop= RNA_def_property(srna, "name", PROP_STRING, PROP_NONE);
 	RNA_def_property_ui_text(prop, "Name", "");
+	RNA_def_property_string_funcs(prop, NULL, NULL, "rna_BoneGroup_name_set");
 	RNA_def_struct_name_property(srna, prop);
 	
 	// TODO: add some runtime-collections stuff to access grouped bones