Assert on Cancel button in "Alignment Modification Confirmation" dialog

Test scenario:
1. Open "data/samples/CLUSTALW/COI.aln".
2. Build a phylogenetic tree synchronized with the alignment.
3. Select the first sequence and push F2
4. In "Rename Sequence" dialog type new name: "1"
5. Push OK
6. "Alignment Modification Confirmation" dialog appears
7. Push Cancel
Expected state: Dialog is closed, sequence name is not renamed
Actual state: Assert

Trying to recover from error: Cannot synchronize the tree with the alignment at
src\ov_msa\PhyTrees\MSAEditorTreeViewer.cpp:259
Assertion failed: ok, file src\ov_msa\PhyTrees\MSAEditorTreeViewer.cpp, line 259

Issue is not reproducible in release 1.30, issue is reproducible on master build in debug mode.