Merge lp:~cjwatson/meliae/py3-duck-type-file into lp:meliae

[Colin Watson]

Duck-type files in meliae.loader.load.

The "file" builtin doesn't exist on Python 3, but we really just need to know whether the source object has a "fileno" method, so test for that directly.

[John A Meinel (jameinel)]

review: Approve

=== modified file 'meliae/loader.py'
--- meliae/loader.py	2020-02-03 22:08:03 +0000
+++ meliae/loader.py	2020-03-11 20:35:47 +0000
@@ -528,10 +528,12 @@
     cleanup = None
     if isinstance(source, six.string_types):
         source, cleanup = files.open_file(source)
-        if isinstance(source, file):
-            input_size = os.fstat(source.fileno()).st_size
-        else:
-            input_size = 0
+        input_size = 0
+        if hasattr(source, "fileno"):
+            try:
+                input_size = os.fstat(source.fileno()).st_size
+            except OSError:
+                pass
     elif isinstance(source, (list, tuple)):
         input_size = sum(map(len, source))
     else: