[migration] Ignore IOError from readline.write_history_file (closes #2106621)
We already ignore them when reading the histfile, no reason writing it
back should be any different.
ifnotrql('CWConstraintType X WHERE X name "RQLUniqueConstraint"',ask_confirm=False):rql('INSERT CWConstraintType X: X name "RQLUniqueConstraint"',ask_confirm=False)