diff -up firefox-102.0/third_party/python/PyYAML/lib3/yaml/reader.py.build-ascii-decode-fail-rhel7 firefox-102.0/third_party/python/PyYAML/lib3/yaml/reader.py
--- firefox-102.0/third_party/python/PyYAML/lib3/yaml/reader.py.build-ascii-decode-fail-rhel7	2022-06-23 09:11:39.000000000 +0200
+++ firefox-102.0/third_party/python/PyYAML/lib3/yaml/reader.py	2022-08-16 13:24:31.697757209 +0200
@@ -73,6 +73,8 @@ class Reader(object):
             self.name = "<unicode string>"
             self.check_printable(stream)
             self.buffer = stream+'\0'
+            #self.encoding = 'utf-8'
+            #self.raw_decode = codecs.utf_8_decode
         elif isinstance(stream, bytes):
             self.name = "<byte string>"
             self.raw_buffer = stream
@@ -83,6 +85,11 @@ class Reader(object):
             self.eof = False
             self.raw_buffer = None
             self.determine_encoding()
+        print("DEBUG_OUTPUT:")
+        print(self.name)
+        print(self.encoding)
+        print(self.stream)
+        #print(self.stream.read())
 
     def peek(self, index=0):
         try:
diff -up firefox-102.0/toolkit/components/nimbus/generate/generate_feature_manifest.py.build-ascii-decode-fail-rhel7 firefox-102.0/toolkit/components/nimbus/generate/generate_feature_manifest.py
--- firefox-102.0/toolkit/components/nimbus/generate/generate_feature_manifest.py.build-ascii-decode-fail-rhel7	2022-08-16 14:16:33.432529817 +0200
+++ firefox-102.0/toolkit/components/nimbus/generate/generate_feature_manifest.py	2022-08-17 08:01:38.175878171 +0200
@@ -37,7 +37,7 @@ def generate_feature_manifest(fd, input_
     write_fm_js_headers(fd)
     nimbus_dir_path = pathlib.Path(input_file).parent
     try:
-        with open(input_file, "r") as yaml_input:
+        with open(input_file, "r", encoding="utf-8") as yaml_input:
             data = yaml.safe_load(yaml_input)
             with pathlib.Path(nimbus_dir_path, FEATURE_MANIFEST_SCHEMA).open() as f:
                 schema = json.load(f)
@@ -92,7 +92,7 @@ def generate_platform_feature_manifest(f
         )
 
     try:
-        with open(input_file, "r") as yaml_input:
+        with open(input_file, "r", encoding="utf-8") as yaml_input:
             data = yaml.safe_load(yaml_input)
             fd.write(file_structure(data))
     except (IOError) as e: