get_annotators: use _get_url in place of requests.get.

Note that this will handle errors (e.g. a file that we are not
authorized to access) and raise an exception, rather than trying to
parse the error document.  Previously, 404 errors were handled, but
other types of errors were not.

Author: Benjamin Moody

wfdb/io/download.py

@@ -342,14 +342,16 @@ def get_annotators(db_dir, annotators):
 
     if annotators is not None:
         # Check for an ANNOTATORS file
-        r = requests.get(posixpath.join(db_url, 'ANNOTATORS'))
-        if r.status_code == 404:
+        try:
+            content = _get_url(posixpath.join(db_url, 'ANNOTATORS'))
+        except FileNotFoundError:
             if annotators == 'all':
                 return
             else:
                 raise ValueError('The database %s has no annotation files to download' % db_url)
+
         # Make sure the input annotators are present in the database
-        ann_list = r.content.decode('ascii').splitlines()
+        ann_list = content.decode('ascii').splitlines()
         ann_list = [a.split('\t')[0] for a in ann_list]
 
         # Get the annotation file types required