This is probably not a bash bug, but I could not figure out where it comes from. The problem is: when I "su" in a virtual console I get the message "bash: no job control in this shell", and it is true that next I cannot interrupt processes. Surprinsingly, this bug is not present if I "su" in an xterm running under X. On my system, almost all packages are up-to-date with the latest rawhide releases.
Yet another effect of a broken /bin/login (#36839) *** This bug has been marked as a duplicate of 36839 ***
Thanks a lot for your advice and for the link to the latest util-linux. I spent the whole day inside bash/termcap/readline/ncurses and was about to become crazy!!! Btw, another effect of this bug was that the virtual console is broken by emacs when quitting. Anyway, thanks again ;)))
THAT effect is a feature, of course. #include <vi/forever.h> ;) SCNR