[LyX/2.3.x] Fix inpreamble styles.

[Juergen Spitzmueller]

commit 961b79975c1578c2f35c7c2ff54559d6e54af7a1
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Tue Dec 26 11:40:58 2017 +0100

    Fix inpreamble styles.
    
    (cherry picked from commit e55e9c842f25b4425db362cd5cb487187f34ba2b)
---
 src/Paragraph.cpp |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Paragraph.cpp b/src/Paragraph.cpp
index dd0920b..8830efb 100644
--- a/src/Paragraph.cpp
+++ b/src/Paragraph.cpp
@@ -2428,7 +2428,7 @@ void Paragraph::latex(BufferParams const & bparams,
        if (empty()) {
                // For InTitle commands, we have already opened a group
                // in output_latex::TeXOnePar.
-               if (style.isCommand() && style.intitle) {
+               if (style.isCommand() && (!style.intitle || style.inpreamble)) {
                        os << '{';
                        ++column;
                }
@@ -2468,7 +2468,7 @@ void Paragraph::latex(BufferParams const & bparams,
                        }
                        // For InTitle commands, we have already opened a group
                        // in output_latex::TeXOnePar.
-                       if (style.isCommand() && !style.intitle) {
+                       if (style.isCommand() && (!style.intitle || 
style.inpreamble)) {
                                os << '{';
                                ++column;
                        }