absorb: add a pycompat.bytestr() to fix --edit-lines functionality on Python 3

Differential Revision: https://phab.mercurial-scm.org/D5610

contrib/python3-whitelist

@@ -1,4 +1,5 b''
 test-abort-checkin.t
+test-absorb-edit-lines.t
 test-absorb-filefixupstate.py
 test-absorb-phase.t
 test-absorb-rename.t

hgext/absorb.py

@@ -489,7 +489,8 b' class filefixupstate(object):'
             if l[colonpos - 1:colonpos + 2] != ' : ':
                 raise error.Abort(_('malformed line: %s') % l)
             linecontent = l[colonpos + 2:]
-            for i, ch in enumerate(l[leftpadpos:colonpos - 1]):
+            for i, ch in enumerate(
+                    pycompat.bytestr(l[leftpadpos:colonpos - 1])):
                 if ch == 'y':
                     contents[visiblefctxs[i][0]] += linecontent
         # chunkstats is hard to calculate if anything changes, therefore