FIX: ensure switching the backend while interactive is interactive

tacaswell · tacaswell · commit 20db32a9869e · 2022-05-17T17:05:04.000-04:00
closes #23042 In #22005 we change `pyplot` so that at import time we do not force a switch of the backend and install the repl displayhook. However, this meant that in some cases (primarily through `ipython --pylab`) to end up with a session where `install_repl_displayhook` had never been called.
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -302,6 +302,10 @@ class backend_mod(matplotlib.backend_bases._Backend):
     # See https://github.com/matplotlib/matplotlib/issues/6092
     matplotlib.backends.backend = newbackend
 
+    # make sure the repl display hook is installed if we are interactive
+    if isinteractive():
+        install_repl_displayhook()
+
 
 def _warn_if_gui_out_of_main_thread():
     if (_get_required_interactive_framework(_get_backend_mod())
