Fix compat.py now that bundled libmagic is preferred

magic/compat.py

@@ -5,6 +5,7 @@
 '''
 
 import ctypes
+import os
 
 from collections import namedtuple
 
@@ -16,6 +17,13 @@
 
 _libraries = {}
 _libraries['magic'] = loader.load_lib()
+magic_file = None
+if not os.environ.get("MAGIC"):
+    # wheels package the mime database in this directory
+    # prefer it when no magic file is specified by the user
+    mime_db = os.path.join(os.path.dirname(__file__), 'magic.mgc')
+    if os.path.exists(mime_db):
+        magic_file = mime_db
 
 # Flag constants for open and setflags
 MAGIC_NONE = NONE = 0
@@ -178,7 +186,7 @@ def setflags(self, flags):
         """
         return _setflags(self._magic_t, flags)
 
-    def load(self, filename=None):
+    def load(self, filename=magic_file):
         """
         Must be called to load entries in the colon separated list of database
         files passed as argument or the default database file if no argument