Revert interactive mode determination

Author: mdboom

lib/matplotlib/__init__.py

@@ -1288,12 +1288,7 @@ def interactive(b):
 
 def is_interactive():
     'Return true if plot mode is interactive'
-    # ps1 exists if the python interpreter is running in an
-    # interactive console; sys.flags.interactive is true if a script
-    # is being run via "python -i".
-    b = rcParams['interactive'] and (
-        hasattr(sys, 'ps1') or sys.flags.interactive)
-    return b
+    return rcParams['interactive']
 
 def tk_window_focus():
     """Return true if focus maintenance under TkAgg on win32 is on.