Fix oddities when replacing VST-presets.

VST used the count of available of presets as URI:
 - add 2 presets (1,2)
 - remove first, add another one -> two presets with same URI (2,2)

PluginInfo::get_presets() simply lists all (name only) in a vector.
Plugin::find_presets() uses the URI in a map (unique by URI).

..various ensuing bugs: eg. Plugin::remove_preset() looked up by name,
but didn't check for NULL.

1 files changed, 3 insertions, 0 deletions

diff --git a/libs/ardour/luaproc.cc b/libs/ardour/luaproc.cc
index 436f60bfc4..4bc2c00c8b 100644
--- a/libs/ardour/luaproc.cc
+++ b/libs/ardour/luaproc.cc
@@ -1141,6 +1141,9 @@ LuaProc::do_save_preset (std::string name) {
 		return "";
 	}
 
+	// prevent dups -- just in case
+	t->root()->remove_nodes_and_delete (X_("label"), name);
+
 	std::string uri (preset_name_to_uri (name));
 
 	XMLNode* p = new XMLNode (X_("Preset"));