Update beets to 1.3.18:

Dependencies:
* PyYAML 3.11
* Unidecode 0.4.19
* beets 1.3.18
* colorama 0.3.7
* enum34 1.1.6
* jellyfish 0.5.4
* munkres 1.0.7
* musicbrainzngs 0.6
* mutagen 1.32

libs/beetsplug/zero.py

@@ -0,0 +1,140 @@
+# -*- coding: utf-8 -*-
+# This file is part of beets.
+# Copyright 2016, Blemjhoo Tezoulbr <baobab@heresiarch.info>.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+
+""" Clears tag fields in media files."""
+
+from __future__ import division, absolute_import, print_function
+
+import re
+from beets.plugins import BeetsPlugin
+from beets.mediafile import MediaFile
+from beets.importer import action
+from beets.util import confit
+
+__author__ = 'baobab@heresiarch.info'
+__version__ = '0.10'
+
+
+class ZeroPlugin(BeetsPlugin):
+
+    _instance = None
+
+    def __init__(self):
+        super(ZeroPlugin, self).__init__()
+
+        # Listeners.
+        self.register_listener('write', self.write_event)
+        self.register_listener('import_task_choice',
+                               self.import_task_choice_event)
+
+        self.config.add({
+            'fields': [],
+            'keep_fields': [],
+            'update_database': False,
+        })
+
+        self.patterns = {}
+        self.warned = False
+
+        # We'll only handle `fields` or `keep_fields`, but not both.
+        if self.config['fields'] and self.config['keep_fields']:
+            self._log.warn(u'cannot blacklist and whitelist at the same time')
+
+        # Blacklist mode.
+        if self.config['fields']:
+            self.validate_config('fields')
+            for field in self.config['fields'].as_str_seq():
+                self.set_pattern(field)
+
+        # Whitelist mode.
+        elif self.config['keep_fields']:
+            self.validate_config('keep_fields')
+
+            for field in MediaFile.fields():
+                if field in self.config['keep_fields'].as_str_seq():
+                    continue
+                self.set_pattern(field)
+
+            # These fields should always be preserved.
+            for key in ('id', 'path', 'album_id'):
+                if key in self.patterns:
+                    del self.patterns[key]
+
+    def validate_config(self, mode):
+        """Check whether fields in the configuration are valid.
+
+        `mode` should either be "fields" or "keep_fields", indicating
+        the section of the configuration to validate.
+        """
+        for field in self.config[mode].as_str_seq():
+            if field not in MediaFile.fields():
+                self._log.error(u'invalid field: {0}', field)
+                continue
+            if mode == 'fields' and field in ('id', 'path', 'album_id'):
+                self._log.warn(u'field \'{0}\' ignored, zeroing '
+                               u'it would be dangerous', field)
+                continue
+
+    def set_pattern(self, field):
+        """Set a field in `self.patterns` to a string list corresponding to
+        the configuration, or `True` if the field has no specific
+        configuration.
+        """
+        try:
+            self.patterns[field] = self.config[field].as_str_seq()
+        except confit.NotFoundError:
+            # Matches everything
+            self.patterns[field] = True
+
+    def import_task_choice_event(self, session, task):
+        """Listen for import_task_choice event."""
+        if task.choice_flag == action.ASIS and not self.warned:
+            self._log.warn(u'cannot zero in \"as-is\" mode')
+            self.warned = True
+        # TODO request write in as-is mode
+
+    @classmethod
+    def match_patterns(cls, field, patterns):
+        """Check if field (as string) is matching any of the patterns in
+        the list.
+        """
+        if patterns is True:
+            return True
+        for p in patterns:
+            if re.search(p, unicode(field), flags=re.IGNORECASE):
+                return True
+        return False
+
+    def write_event(self, item, path, tags):
+        """Set values in tags to `None` if the key and value are matched
+        by `self.patterns`.
+        """
+        if not self.patterns:
+            self._log.warn(u'no fields, nothing to do')
+            return
+
+        for field, patterns in self.patterns.items():
+            if field in tags:
+                value = tags[field]
+                match = self.match_patterns(tags[field], patterns)
+            else:
+                value = ''
+                match = patterns is True
+
+            if match:
+                self._log.debug(u'{0}: {1} -> None', field, value)
+                tags[field] = None
+                if self.config['update_database']:
+                    item[field] = None