Report encoding errors nicely.

cdist/__init__.py

@@ -100,6 +100,7 @@ class CdistEntityError(Error):
         for name, path in stdpaths:
             if name not in result:
                 result[name] = []
+            try:
                 if os.path.exists(path) and os.path.getsize(path) > 0:
                     output = []
                     label_begin = name + ":" + header_name
@@ -111,6 +112,11 @@ class CdistEntityError(Error):
                         output.append(fd.read())
                     output.append('\n')
                     result[name].append(''.join(output))
+            except UnicodeError as ue:
+                result[name].append(('Cannot output {}:{} due to: {}.\n'
+                                     'You can try to read the error file "{}"'
+                                     ' yourself.').format(
+                                         name, header_name, ue, path))
         return result
 
     def _stderr(self):