Remove equality check from fuzz test & improve version coverage

The equality check was low value as it didn't do more than check some
simple value comparisons in the source file, and it consumed a large
amout of input data which made the test less efficient.

Also adds `None` to the possible bundle version values to test source
code branches executed when `Bundle.version = None`.

Finally, adds new dict entries suggested by LibFuzzer during local runs.

fuzzing/dictionaries/fuzz_bundle.dict

@@ -1,2 +1,5 @@
 "# v2 git bundle"
 "# v3 git bundle"
+"\\001\\000\\000\\000"
+"\\001\\000"
+"\\377\\377\\377\\377\\377\\377\\377\\377"

fuzzing/fuzz-targets/fuzz_bundle.py

@@ -13,7 +13,7 @@ with atheris.instrument_imports():
 def TestOneInput(data):
     fdp = EnhancedFuzzedDataProvider(data)
     bundle = Bundle()
-    bundle.version = fdp.PickValueInList([2, 3])
+    bundle.version = fdp.PickValueInList([2, 3, None])
     bundle.references = {fdp.ConsumeRandomString(): fdp.ConsumeBytes(20)}
     bundle.prerequisites = [(fdp.ConsumeBytes(20), fdp.ConsumeRandomBytes())]
     bundle.capabilities = {
@@ -31,37 +31,18 @@ def TestOneInput(data):
     try:
         bundle_file = BytesIO()
         write_bundle(bundle_file, bundle)
-    except (AttributeError, UnicodeEncodeError) as e:
+        _ = read_bundle(bundle_file)
+    except (AttributeError, UnicodeEncodeError, AssertionError) as e:
         expected_exceptions = [
             "'bytes' object has no attribute 'encode'",
             "surrogates not allowed",
+            "unsupported bundle format header",
         ]
         if is_expected_exception(expected_exceptions, e):
             return
         else:
             raise e
 
-    bundle_file.seek(0)
-    _ = read_bundle(bundle_file)
-
-    # Test __eq__ method
-    # Create a different bundle for inequality testing _after_ read/write tests.
-    # The read/write tests may have consumed all the `data` via the `fdp` "Consume" methods, so we build the second
-    # bundle _after_ so those tests can execute even before the fuzzing engine begins providing large enough inputs to
-    # populate the second bundle's fields.
-    other_bundle = Bundle()
-    other_bundle.version = bundle.version
-    other_bundle.references = {fdp.ConsumeRandomString(): fdp.ConsumeBytes(20)}
-    other_bundle.prerequisites = [(fdp.ConsumeBytes(20), fdp.ConsumeRandomBytes())]
-    other_bundle.capabilities = {
-        fdp.ConsumeRandomString(): fdp.ConsumeRandomString(),
-    }
-    b2 = BytesIO()
-    write_pack_objects(b2.write, [])
-    b2.seek(0)
-    other_bundle.pack_data = PackData.from_file(b2)
-    _ = bundle != other_bundle
-
 
 def main():
     atheris.Setup(sys.argv, TestOneInput)