* exceptions.c (throw_exception): Don't disable the current
display.
* printcmd.c (disable_current_display_cleanup): New function.
(do_one_display): Install a cleanup to disable the current display
if doing the display throws.
gdb/testsuite/
* gdb.trace/unavailable.exp (test_maybe_regvar_display): New
procedure.
(gdb_collect_args_test, gdb_collect_locals_test): Use it.