[LyX/master] Don't add localswitch if no language changes

[Juergen Spitzmueller]

commit 7018d3641f693967bb8bade86488a495cd2e976b
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Fri Apr 27 18:27:21 2018 +0200

    Don't add localswitch if no language changes
---
 src/output_latex.cpp |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/output_latex.cpp b/src/output_latex.cpp
index dcf10a7..c36ed25 100644
--- a/src/output_latex.cpp
+++ b/src/output_latex.cpp
@@ -838,9 +838,11 @@ void TeXOnePar(Buffer const & buf,
                lang_end_command = "}";
                lang_command_termination.clear();
        }
+       
+       bool const localswitch_needed = localswitch && par_lang != outer_lang;
 
        // localswitches need to be closed and reopened at each par
-       if ((par_lang != prev_lang || localswitch)
+       if ((par_lang != prev_lang || localswitch_needed)
             // check if we already put language command in TeXEnvironment()
             && !(style.isEnvironment()
                  && (pit == 0 || (priorpar->layout() != par.layout()
@@ -1115,7 +1117,7 @@ void TeXOnePar(Buffer const & buf,
                &&((nextpar && par_lang != nextpar_lang)
                   || (runparams.isLastPar && par_lang != outer_lang));
 
-       if (localswitch
+       if (localswitch_needed
            || (intitle_command && using_begin_end)
            || closing_rtl_ltr_environment
            || ((runparams.isLastPar || close_lang_switch)