merge: use constants for merge state record types merge.py is using multiple discrete sets of 1 and 2 letter constants to define types and behavior. To the uninitiated, the code is very difficult to reason about. I didn't even realize there were multiple sets of constants in play initially! We begin our sanity injection with merge state records. The record types (which are serialized to disk) are now defined in RECORD_* constants. Differential Revision: https://phab.mercurial-scm.org/D2698

#require docutils gettext

Error: the current ro localization has some rst defects exposed by
moving pager to core. These two warnings about references are expected
until the localization is corrected.
  $ $TESTDIR/check-gendoc ro
  checking for parse errors
  gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.
  gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.