This bug is a duplicate of https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1070887 : the reportbug output led me to believe had not been submitted (and the acknowledgement was late), so I restarted reportbug and configured it to resend my report explicitly via evolution.
In fact, both submission worked, but the second is but a duplicate of the first.
My apologies for the noise...
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Rmmanuel Charpentier