[bandcamp:album] Make path optional (Closes #4461)

youtube_dl/extractor/bandcamp.py

@@ -106,7 +106,7 @@ class BandcampIE(InfoExtractor):
 
 class BandcampAlbumIE(InfoExtractor):
     IE_NAME = 'Bandcamp:album'
-    _VALID_URL = r'https?://(?:(?P<subdomain>[^.]+)\.)?bandcamp\.com(?:/album/(?P<title>[^?#]+))'
+    _VALID_URL = r'https?://(?:(?P<subdomain>[^.]+)\.)?bandcamp\.com(?:/album/(?P<title>[^?#]+))?'
 
     _TESTS = [{
         'url': 'http://blazo.bandcamp.com/album/jazz-format-mixtape-vol-1',
@@ -141,6 +141,12 @@ class BandcampAlbumIE(InfoExtractor):
             'title': 'Hierophany of the Open Grave',
         },
         'playlist_mincount': 9,
+    }, {
+        'url': 'http://dotscale.bandcamp.com',
+        'info_dict': {
+            'title': 'Loom',
+        },
+        'playlist_mincount': 7,
     }]
 
     def _real_extract(self, url):