Resolves: tdf#139974 Do not munge character after forced line break

A classical +-1 error..

Change-Id: I8b6bc0843fa585d8a710c74f757098ab9c6f823d
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/128637
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins
diff --git a/editeng/source/editeng/impedit2.cxx b/editeng/source/editeng/impedit2.cxx
index b19d1b4..0fd1c00 100644
--- a/editeng/source/editeng/impedit2.cxx
+++ b/editeng/source/editeng/impedit2.cxx
@@ -2730,8 +2730,10 @@ EditPaM ImpEditEngine::ImpInsertText(const EditSelection& aCurSel, const OUStrin
            if (nChars > MAXCHARSINPARA)
            {
                sal_Int32 nMaxNewChars = std::max<sal_Int32>(0, MAXCHARSINPARA - nExistingChars);
                nEnd -= ( aLine.getLength() - nMaxNewChars ); // Then the characters end up in the next paragraph.
                aLine = aLine.copy( 0, nMaxNewChars );        // Delete the Rest...
                // Remaining characters end up in the next paragraph. Note that
                // new nStart will be nEnd+1 below so decrement by one more.
                nEnd -= (aLine.getLength() - nMaxNewChars + 1);
                aLine = aLine.copy( 0, nMaxNewChars );  // Delete the Rest...
            }
            if ( IsUndoEnabled() && !IsInUndo() )
                InsertUndo(std::make_unique<EditUndoInsertChars>(pEditEngine, CreateEPaM(aPaM), aLine));