Restore matplotlib pyinstaller hook which is still needed in 3.3

dist_assets/pyinstaller_hooks/hook-matplotlib.backends.py

@@ -0,0 +1,78 @@
+# This apes hook-matplotlib.backends.py, but REMOVES backends, all but
+# the ones in the list below.
+# Courtesy of https://github.com/bpteague/cytoflow/blob/70f9291/packaging/hook-matplotlib.backends.py
+
+KEEP = ["WXAgg", "WX", "agg"]
+
+from PyInstaller.compat import is_darwin
+from PyInstaller.utils.hooks import (
+    eval_statement, exec_statement, logger)
+
+
+def get_matplotlib_backend_module_names():
+    """
+    List the names of all matplotlib backend modules importable under the
+    current Python installation.
+    Returns
+    ----------
+    list
+        List of the fully-qualified names of all such modules.
+    """
+    # Statement safely importing a single backend module.
+    import_statement = """
+import os, sys
+# Preserve stdout.
+sys_stdout = sys.stdout
+try:
+    # Redirect output printed by this importation to "/dev/null", preventing
+    # such output from being erroneously interpreted as an error.
+    with open(os.devnull, 'w') as dev_null:
+        sys.stdout = dev_null
+        __import__('%s')
+# If this is an ImportError, print this exception's message without a traceback.
+# ImportError messages are human-readable and require no additional context.
+except ImportError as exc:
+    sys.stdout = sys_stdout
+    print(exc)
+# Else, print this exception preceded by a traceback. traceback.print_exc()
+# prints to stderr rather than stdout and must not be called here!
+except Exception:
+    sys.stdout = sys_stdout
+    import traceback
+    print(traceback.format_exc())
+"""
+
+    # List of the human-readable names of all available backends.
+    backend_names = eval_statement(
+        'import matplotlib; print(matplotlib.rcsetup.all_backends)')
+
+    # List of the fully-qualified names of all importable backend modules.
+    module_names = []
+
+    # If the current system is not OS X and the "CocoaAgg" backend is available,
+    # remove this backend from consideration. Attempting to import this backend
+    # on non-OS X systems halts the current subprocess without printing output
+    # or raising exceptions, preventing its reliable detection.
+    if not is_darwin and 'CocoaAgg' in backend_names:
+        backend_names.remove('CocoaAgg')
+
+    # For safety, attempt to import each backend in a unique subprocess.
+    for backend_name in backend_names:
+        if backend_name in KEEP:
+            continue
+
+        module_name = 'matplotlib.backends.backend_%s' % backend_name.lower()
+        stdout = exec_statement(import_statement % module_name)
+
+        # If no output was printed, this backend is importable.
+        if not stdout:
+            module_names.append(module_name)
+            logger.info('  Matplotlib backend "%s": removed' % backend_name)
+
+    return module_names
+
+# Freeze all importable backends, as PyInstaller is unable to determine exactly
+# which backends are required by the current program.
+e=get_matplotlib_backend_module_names()
+print(e)
+excludedimports = e