Implement better GPG output decoding

debianmemberportfolio/model/keyringanalyzer.py

@@ -160,7 +160,11 @@ def process_keyrings():
             stdout=subprocess.PIPE)
         fpr = None
         for line in proc.stdout.readlines():
-            fpr = process_gpg_list_keys_line(line.decode('utf8'), fpr)
+            try:
+                line = line.decode('utf8')
+            except UnicodeDecodeError:
+                line = line.decode('iso8859-1')
+            fpr = process_gpg_list_keys_line(line, fpr)
         retcode = proc.wait()
         if retcode != 0:
             logging.error("subprocess ended with return code %d", retcode)