font-patcher: Fix unexpected 'Book' SubFamily

[why]
Sometimes we set an empty string as SubFamily name. That ends up as
'Book' which is unexpected.

[how]
The translation from empty to "Book" is done by Fontforge, at least
with version 20220308.

Make sure we always have a SubFamily, and if we don't that must be a
'Regular'.

[note]
This was only a problem with the old naming engine. --makegroups got
this right always.

Fixes: #1046

Signed-off-by: Fini Jastrow <ulf.fini.jastrow@desy.de>

bin/scripts/name_parser/FontnameParser.py

@@ -302,6 +302,9 @@ def rename_font(self, font):
         sfnt_list = []
         TO_DEL = ['Family', 'SubFamily', 'Fullname', 'Postscriptname', 'Preferred Family',
                 'Preferred Styles', 'Compatible Full', 'WWS Family', 'WWS Subfamily']
+        # Remove these entries in all languages and add (at least the vital ones) some
+        # back, but only as 'English (US)'. This makes sure we do not leave contradicting
+        # names over different languages.
         for l, k, v in list(font.sfnt_names):
             if not k in TO_DEL:
                 sfnt_list += [( l, k, v )]

font-patcher

@@ -6,7 +6,7 @@
 from __future__ import absolute_import, print_function, unicode_literals
 
 # Change the script version when you edit this script:
-script_version = "3.4.0"
+script_version = "3.4.1"
 
 version = "2.3.0-RC"
 projectName = "Nerd Fonts"
@@ -512,13 +512,16 @@ class font_patcher:
             subFamily = fallbackStyle
 
         # some fonts have inaccurate 'SubFamily', if it is Regular let us trust the filename more:
-        if subFamily == "Regular":
+        if subFamily == "Regular" and len(fallbackStyle):
             subFamily = fallbackStyle
 
         # This is meant to cover the case where the SubFamily is "Italic" and the filename is *-BoldItalic.
         if  len(subFamily) < len(fallbackStyle):
             subFamily = fallbackStyle
 
+        if len(subFamily) == 0:
+            subFamily = "Regular"
+
         if self.args.windows:
             maxFamilyLength = 31
             maxFontLength = maxFamilyLength - len('-' + subFamily)