[LyX/2.2.x] Fix thinko in Buffer::preview. It is possible for this routine to be called when we do not have a cloned Buffer, namely, if we do not have EXPORT_in_THREAD defined.

[Richard Heck]

commit b02a93d7e809775b58f21e9b56d19f858e6fd3ba
Author: Richard Heck <rgh...@lyx.org>
Date:   Sun Jul 10 01:12:42 2016 -0400

    Fix thinko in Buffer::preview. It is possible for this routine to
    be called when we do not have a cloned Buffer, namely, if we do not
    have EXPORT_in_THREAD defined.
    
    (cherry picked from commit d8aab4af9e6e72c835f78ba54a46687b870c25fa)
---
 src/Buffer.cpp |   21 +++++++++------------
 status.22x     |    2 ++
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index d9dc38f..22c993c 100644
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -4311,10 +4311,10 @@ Buffer::ExportStatus Buffer::preview(string const & 
format, bool includeall) con
        ExportStatus const status = doExport(format, true, false, result_file);
        FileName const previewFile(result_file);
 
-       LATTEST (isClone());
-       d->cloned_buffer_->d->preview_file_ = previewFile;
-       d->cloned_buffer_->d->preview_format_ = format;
-       d->cloned_buffer_->d->preview_error_ = (status != ExportSuccess);
+       Impl * theimpl = isClone() ? d->cloned_buffer_->d : d;
+       theimpl->preview_file_ = previewFile;
+       theimpl->preview_format_ = format;
+       theimpl->preview_error_ = (status != ExportSuccess);
 
        if (status != ExportSuccess)
                return status;
@@ -4323,14 +4323,11 @@ Buffer::ExportStatus Buffer::preview(string const & 
format, bool includeall) con
                        return PreviewError;
                else
                        return PreviewSuccess;
-       }
-       else {
-               // Successful export but no output file?
-               // Probably a bug in error detection.
-               LATTEST (status != ExportSuccess);
-
-               return status;
-       }
+       } 
+       // Successful export but no output file?
+       // Probably a bug in error detection.
+       LATTEST(status != ExportSuccess);
+       return status;
 }
 
 
diff --git a/status.22x b/status.22x
index 1c25a8b..4859299 100644
--- a/status.22x
+++ b/status.22x
@@ -89,6 +89,8 @@ What's new
 
 - Fix command clash between beamer and covington (from the Linguistics module).
 
+- Fix crash on Buffer preview when not exporting in thread.
+
 
 * LYX2LYX