stringutil: if we get a memoryview in escapestr, coerce it to bytes

Otherwise we get an exception. Sadly, this manifesting deep inside the
wireproto code, inside a future. For some reason the exception was
/causing a hang/ rather than actually propagating out, which seems
like it might merit some investigation in the future.

Differential Revision: https://phab.mercurial-scm.org/D4256

mercurial/utils/stringutil.py

@@ -427,6 +427,8 b' def ellipsis(text, maxlength=400):'
     return encoding.trim(text, maxlength, ellipsis='...')
 
 def escapestr(s):
+    if isinstance(s, memoryview):
+        s = bytes(s)
     # call underlying function of s.encode('string_escape') directly for
     # Python 3 compatibility
     return codecs.escape_encode(s)[0]