Make re-exec work with "dropbearmulti dropbear" The re-exec needs to know to use the dropbearmulti binary instead. Add a test for this case.

attrs==21.2.0
iniconfig==1.1.1
packaging==21.0
pluggy==1.0.0
py==1.10.0
pyparsing==2.4.7
pytest==6.2.5
toml==0.10.2
psutil==5.9.0