Comment # 2 on bug 920024 from Dr. Werner Fink

(In reply to Bernhard Wiedemann from comment #1)

Does this also work if variable $COMP_WORDBREAKS includes the colon at the end
of its value;

 d136:~ # echo $COMP_WORDBREAKS 
 "'><=;|&(:

please note that the package osc includes a bug which is fixed a long time ago
but never reached the distribution, compare with

  /etc/profile.d/osc.sh

and the line

  COMP_WORDBREAKS="${COMP_WORDBREAKS//:}"

therein.