temp command loop reply buffer not emptied

# normal:
2023-12-01 06:25:17.582Z smb        20 tcpip.py:93 new cmd: ?t
2023-12-01 06:25:17.583Z smb        20 tcpip.py:76 reply: 154.8147,276.4454,157.0904,134.6539,278.0847,400.0000,400.0000,400.0000,400.0000,400.0000,162.1743,162.7146
2023-12-01 06:25:19.200Z smb        20 tcpip.py:93 new cmd: ?F1
2023-12-01 06:25:19.209Z smb        20 tcpip.py:76 reply: 0

# glitch, either in heater read back code or command loop:
2023-12-01 06:25:19.222Z smb        20 tcpip.py:93 new cmd: ?L1
2023-12-01 06:25:22.228Z smb        30 tcpip.py:70 no reply to command!
2023-12-01 06:25:22.465Z sensors    30 sensor_loop.py:57 loop period is too short. last=1.70141e+09, next=1.70141e+09, dt=-2.31219

2023-12-01 06:25:22.467Z smb        20 tcpip.py:93 new cmd: ?V1
2023-12-01 06:25:22.468Z smb        20 tcpip.py:76 reply: 1

# after this, the command outputs are out of sync.
2023-12-01 06:25:32.394Z smb        20 tcpip.py:93 new cmd: ?t
2023-12-01 06:25:32.395Z smb        20 tcpip.py:76 reply: 0.0
2023-12-01 06:25:33.905Z smb        20 tcpip.py:93 new cmd: ?F1
2023-12-01 06:25:33.906Z smb        20 tcpip.py:76 reply: 154.8151,276.4445,157.0902,134.6539,278.0853,400.0000,400.0000,400.0000,400.0000,400.0000,162.1750,162.7149