Properly generate locale codes for 3 letter region codes

These have to be prefixed with b+.
Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/lang/models.py

@@ -122,6 +122,9 @@ class LanguageManager(models.Manager):
         """
         Language code sanitization.
         """
+        # Strip b+ prefix from Android
+        if code.startswith('b+'):
+            code = code[2:]
         code = code.replace(' ', '').replace('(', '').replace(')', '')
         while code[-1].isdigit():
             code = code[:-1]

weblate/trans/formats.py

@@ -1153,6 +1153,8 @@ class AndroidFormat(FileFormat):
         """
         Does any possible formatting needed for language code.
         """
+        if len(code) == 3:
+            return 'b+{0}'.format(code)
         return code.replace('_', '-r')