[pitivi] pluginmanager: Fix checking for user_plugins_dir (typo)

[Alexandru Băluț <alexbalut src gnome org>]

commit 8d9a5ede08f7b4621c402b78593ce5a00bc5b6bf
Author: Michał Górny <mgorny gentoo org>
Date:   Tue Oct 17 20:57:22 2017 +0200

    pluginmanager: Fix checking for user_plugins_dir (typo)

 pitivi/pluginmanager.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/pitivi/pluginmanager.py b/pitivi/pluginmanager.py
index c9a0ebc..f8e765e 100644
--- a/pitivi/pluginmanager.py
+++ b/pitivi/pluginmanager.py
@@ -120,7 +120,7 @@ class PluginManager(Loggable):
         user_plugins_dir = get_user_plugins_dir()
         if os.path.exists(plugins_dir):
             self.engine.add_search_path(plugins_dir)
-        if os.path.exists(plugins_dir):
+        if os.path.exists(user_plugins_dir):
             self.engine.add_search_path(user_plugins_dir)
 
     @staticmethod