diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -1938,7 +1938,12 @@ def writebundle(
             raise error.Abort(
                 _(b'old bundle types only supports v1 changegroups')
             )
+
+        # HG20 is the case without 2 values to unpack, but is handled above.
+        # pytype: disable=bad-unpacking
         header, comp = bundletypes[bundletype]
+        # pytype: enable=bad-unpacking
+
         if comp not in util.compengines.supportedbundletypes:
             raise error.Abort(_(b'unknown stream compression type: %s') % comp)
         compengine = util.compengines.forbundletype(comp)
diff --git a/mercurial/bundlecaches.py b/mercurial/bundlecaches.py
--- a/mercurial/bundlecaches.py
+++ b/mercurial/bundlecaches.py
@@ -5,6 +5,10 @@
 
 import collections
 
+from typing import (
+    cast,
+)
+
 from .i18n import _
 
 from .thirdparty import attr
@@ -247,7 +251,7 @@ def parsebundlespec(repo, spec, strict=T
     # required to apply it. If we see this metadata, compare against what the
     # repo supports and error if the bundle isn't compatible.
     if version == b'packed1' and b'requirements' in params:
-        requirements = set(params[b'requirements'].split(b','))
+        requirements = set(cast(bytes, params[b'requirements']).split(b','))
         missingreqs = requirements - requirementsmod.STREAM_FIXED_REQUIREMENTS
         if missingreqs:
             raise error.UnsupportedBundleSpecification(
diff --git a/mercurial/utils/stringutil.py b/mercurial/utils/stringutil.py
--- a/mercurial/utils/stringutil.py
+++ b/mercurial/utils/stringutil.py
@@ -723,11 +723,15 @@ def escapestr(s: bytes) -> bytes:
         s = bytes(s)
     # call underlying function of s.encode('string_escape') directly for
     # Python 3 compatibility
+    # pytype: disable=bad-return-type
     return codecs.escape_encode(s)[0]  # pytype: disable=module-attr
+    # pytype: enable=bad-return-type
 
 
 def unescapestr(s: bytes) -> bytes:
+    # pytype: disable=bad-return-type
     return codecs.escape_decode(s)[0]  # pytype: disable=module-attr
+    # pytype: enable=bad-return-type
 
 
 def forcebytestr(obj):