The merge tool is working beautifully again.
Thanks a lot.
BTW, When I used today the propagate tool with the staged strings produced by the merge branch operation, many white-shaded strings appeared. If I try to commit this white shaded strings (already existing in that branch), those strings ended up being submitted to myself (lang pack maintainer) by myself. No harm is done, but I had to reject my own contributions, which is kind of odd. I'll think no further about this; I'll be more carefull in the future to prevent this odd behaviour.