[LyX/master] Correctly handle internal clipboard in cell paste

[Juergen Spitzmueller]

commit c24c82d986ce2364ae2992a9a8f074061b688c37
Author: Juergen Spitzmueller <spitz at lyx.org>
Date:   Thu Feb 11 16:45:27 2021 +0100

    Correctly handle internal clipboard in cell paste
---
 src/insets/InsetTabular.cpp |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/src/insets/InsetTabular.cpp b/src/insets/InsetTabular.cpp
index 7c340b0..e01c55c 100644
--- a/src/insets/InsetTabular.cpp
+++ b/src/insets/InsetTabular.cpp
@@ -5332,7 +5332,8 @@ void InsetTabular::doDispatch(Cursor & cur, FuncRequest & cmd)
 					break;
 				}
 			}
-			else if (theClipboard().hasTextContents(Clipboard::LyXTextType)) {
+			else if (!theClipboard().isInternal()
+				 && theClipboard().hasTextContents(Clipboard::LyXTextType)) {
 				// This might be tabular data from another LyX instance. Check!
 				docstring const clip =
 					theClipboard().getAsText(Clipboard::PlainTextType);