encoding: force a few Errors to bytes before passing to `error.Abort`

I'm not sure what changed before pytype 09-09-2021 (from 04-15-2021), but these
started getting flagged.  PyCharm also flagged these.  This fixes the following:

    File "/mnt/c/Users/Matt/hg/mercurial/encoding.py", line 243, in fromlocal: Function Abort.__init__ was called with the wrong arguments [wrong-arg-types]
             Expected: (self, message: Union[bytearray, bytes, memoryview], ...)
      Actually passed: (self, message: LookupError, ...)
    File "/mnt/c/Users/Matt/hg/mercurial/encoding.py", line 309, in lower: Function Abort.__init__ was called with the wrong arguments [wrong-arg-types]
             Expected: (self, message: Union[bytearray, bytes, memoryview], ...)
      Actually passed: (self, message: LookupError, ...)
    File "/mnt/c/Users/Matt/hg/mercurial/encoding.py", line 336, in upperfallback: Function Abort.__init__ was called with the wrong arguments [wrong-arg-types]
             Expected: (self, message: Union[bytearray, bytes, memoryview], ...)
      Actually passed: (self, message: LookupError, ...)
    Called from (traceback):
      line 391, in current file
      line 348, in get
      line 318, in upper

Differential Revision: https://phab.mercurial-scm.org/D11467

mercurial/encoding.py

@@ -240,7 +240,9 b' def fromlocal(s):'
             b"decoding near '%s': %s!" % (sub, pycompat.bytestr(inst))
         )
     except LookupError as k:
-        raise error.Abort(k, hint=b"please check your locale settings")
+        raise error.Abort(
+            pycompat.bytestr(k), hint=b"please check your locale settings"
+        )
 
 
 def unitolocal(u):
@@ -306,7 +308,9 b' def lower(s):'
     except UnicodeError:
         return s.lower()  # we don't know how to fold this except in ASCII
     except LookupError as k:
-        raise error.Abort(k, hint=b"please check your locale settings")
+        raise error.Abort(
+            pycompat.bytestr(k), hint=b"please check your locale settings"
+        )
 
 
 def upper(s):
@@ -333,7 +337,9 b' def upperfallback(s):'
     except UnicodeError:
         return s.upper()  # we don't know how to fold this except in ASCII
     except LookupError as k:
-        raise error.Abort(k, hint=b"please check your locale settings")
+        raise error.Abort(
+            pycompat.bytestr(k), hint=b"please check your locale settings"
+        )
 
 
 if not _nativeenviron: