py3: convert return values of inspect.getabsfile() to bytes

It's weird that python docs for inspect does not mention getabsfile().

Differential Revision: https://phab.mercurial-scm.org/D6033

mercurial/chgserver.py

@@ -140,7 +140,7 b' def _getmtimepaths(ui):'
     files = [pycompat.sysexecutable]
     for m in modules:
         try:
-            files.append(inspect.getabsfile(m))
+            files.append(pycompat.fsencode(inspect.getabsfile(m)))
         except TypeError:
             pass
     return sorted(set(files))