FIX: fix importing backend with non-ascii characters

tacaswell · tacaswell · commit 69b4233a7d8e · 2018-08-28T18:01:41.000-04:00
The issue is that the lines coming out of `traceback.format_stack()` are bytes (aka python2 str). This file uses `unicode_literals` so the string literals are unicode. If any of the paths in the stack have non-ascii we get UnicodeDecode exceptions when trying to convert the byte strings to unicode with ascii. The `str` calls will have no effect on python3 and down-cast the unicode to bytes so the operations will work. A better fix would be to sort out what encoding the bytes from `format_stack` are in and convert them to unicode, but this is simpler and is unlikely to make things worse than they were. closes matplotlib#11955
diff --git a/lib/matplotlib/backends/__init__.py b/lib/matplotlib/backends/__init__.py
@@ -12,10 +12,11 @@
 _log = logging.getLogger(__name__)
 
 backend = matplotlib.get_backend()
-_backend_loading_tb = "".join(
+# the `str` calls here are to make non-ascii paths work on python2
+_backend_loading_tb = str("").join(
     line for line in traceback.format_stack()
     # Filter out line noise from importlib line.
-    if not line.startswith('  File "<frozen importlib._bootstrap'))
+    if not line.startswith(str('  File "<frozen importlib._bootstrap')))
 
 
 def pylab_setup(name=None):
