Log Message:
Update to 1.4.11. From the changelog:

API:

* MSet::SNIPPET_CJK_NGRAM - new flag for use with MSet::snippet() to enable
  support for selecting and highlighting snippets which works with the
  QueryParser and TermGenerator FLAG_CJK_NGRAM flags.  This mode can also be
  enabled by setting environment variable XAPIAN_CJK_NGRAM to a non-empty
  value.  (There was nominally already support for XAPIAN_CJK_NGRAM in
  MSet::snippet(), but it didn't work usefully - the highlighting added was all
  empty start/end pairs at the end of the span of CJK characters containing the
  CJK ngram terms, which to the user would typically look like it was selecting
  the end of the text and not highlighting anything).

* Deprecate XAPIAN_CJK_NGRAM environment variable.  There are now flags which
  can be used instead in all cases, and there's sadly no portable thread-safe
  way to read an environment variable so checking environment variables is
  problematic in library code that may be used in multithreaded programs.

* Query::OP_ELITE_SET currently incorrectly recursively flattens any OP_OR (or
  OP_OR-like) subqueries into the list of subqueries it selects from - until
  that's fixed, we now select from the full exploded list rather than the last
  n (where n is the number of direct subqueries of the OP_ELITE_SET).

testsuite:

* Testcases which need a generated database now get run with a sharded
  database.

* Avoid using strerror() in the testsuite which removes an obstacle to running
  tests in parallel in separate threads.

matcher:

* Extend detection of cases of OP_SYNONYM with disjoint subqueries (which means
  we don't need document length) which was added in 1.4.8 - we now detect when
  all subqueries are different terms, or when all subqueries are
  non-overlapping wildcards.  The second case is what QueryParser produces for
  a wildcard or partial query with a query prefix which maps to more than one
  term prefix.

glass backend:

* Handle an empty value slot lower bound gracefully.  This shouldn't happen for
  a non-empty slot, but has been reported by a notmuch user so it seems there
  is (or perhaps was as the database was several years old) a way it can come
  about.  We now check for this situation and set the smallest possible valid
  lower bound instead, so other code assuming a valid lower bound will work
  correctly.  Reported by jb55.

chert backend:

* Handle an empty value slot lower bound gracefully, equivalent to the change
  made for glass.

documentation:

* HACKING: We no longer use auto_ptr<>.

* NEWS: Correct factual error in old entry - the 0.4.1 release was Open Muscat
  not OmSee (the OmSee name was only applied after that final release was made,
  and only used internally to BrightStation).

portability:

* Suppress more clang -Wself-assign-overloaded warnings in testcases which are
  deliberately testing handling of self-assignment.

* Add missing includes of <cerrno>.  Fixes #776, reported by Matthieu Gautier.

debug code:

* When configured with --enable-log, the O_SYNC flag was always specified when
  opening the logfile, with the intention that the most recent log entries
  wouldn't get lost if there was a crash, but O_SYNC can incur a significant
  performance overhead and most debugging is not of such crashes.  So we no
  longer specify O_SYNC by default, but you can now request synchronous logging
  by including %! anywhere in the filename specified with XAPIAN_DEBUG_LOG
  (the %! is replaced with the empty string).  We also now use O_DSYNC if
  available in preference to O_SYNC, since the mtime of the log file isn't
  important.