fetchart: correctly handle path encoding

* Ensure that `config.as_str_seq()` returns a list of unicode objects.
* Map these to bytestring paths so we can compare them to other paths.

Fixes #887

beets/util/confit.py

@@ -1077,16 +1077,21 @@ class StrSeq(Template):
                 return value.split()
             else:
                 return [value]
-        else:
-            try:
-                value = list(value)
-            except TypeError:
-                self.fail('must be a whitespace-separated string or a list',
-                          view, True)
-            if all(isinstance(x, BASESTRING) for x in value):
-                return value
+
+        try:
+            value = list(value)
+        except TypeError:
+            self.fail('must be a whitespace-separated string or a list',
+                      view, True)
+
+        def convert(x):
+            if isinstance(x, unicode):
+                return x
+            elif isinstance(x, BASESTRING):
+                return x.decode('utf8', 'ignore')
             else:
                 self.fail('must be a list of strings', view, True)
+        return map(convert, value)
 
 
 class Filename(Template):

beetsplug/fetchart.py

@@ -234,6 +234,7 @@ def art_for_album(album, paths, maxwidth=None, local_only=False):
 
     # Local art.
     cover_names = config['fetchart']['cover_names'].as_str_seq()
+    cover_names = map(util.bytestring_path, cover_names)
     cautious = config['fetchart']['cautious'].get(bool)
     if paths:
         for path in paths:

test/helper.py

@@ -253,7 +253,7 @@ class TestHelper(object):
         values['title'] = values['title'].format(item_count)
         item = Item(**values)
         item.add(self.lib)
-        if not 'path' in values_:
+        if 'path' not in values_:
             item['path'] = item.destination()
             item.store()
         return item