[3.6] bpo-8231: Call idlelib.IdleConf.GetUserCfgDir only once. (GH-2629) (#2631)

(cherry picked from commit 223c7e7)
diff --git a/Lib/idlelib/pyshell.py b/Lib/idlelib/pyshell.py
index be7bd3d..47df744 100755
--- a/Lib/idlelib/pyshell.py
+++ b/Lib/idlelib/pyshell.py
@@ -117,8 +117,8 @@
         self.text.bind("<<clear-breakpoint-here>>", self.clear_breakpoint_here)
         self.text.bind("<<open-python-shell>>", self.flist.open_shell)
 
-        self.breakpointPath = os.path.join(idleConf.GetUserCfgDir(),
-                                           'breakpoints.lst')
+        self.breakpointPath = os.path.join(
+                idleConf.userdir, 'breakpoints.lst')
         # whenever a file is changed, restore breakpoints
         def filename_changed_hook(old_hook=self.io.filename_change_hook,
                                   self=self):