hush: fix a bunch of obscure while/until/continue bugs

function                                             old     new   delta
run_list                                            1159    1214     +55
done_pipe                                            106     123     +17
done_command                                          86      98     +12
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(add/remove: 0/0 grow/shrink: 3/0 up/down: 84/0)               Total: 84 bytes

10 files changed