We previously used FALSE for that but in the end it does not make much
sense. Luckily for us this does not represent a breaking change since
existing code will keep to work, so we can safely push this change into
the next patch release.
Now Predis\Command\ScriptedCommand uses EVALSHA instead of EVAL internally
so that performances should be better since the client do not resend the
Lua script body on each call.
Plain EVALSHA commands are not affected and will return or throw the error.
With a negative number Predis will count from the end of the arguments list
to calculate the actual number of keys that will be interpreted as elements
for `KEYS` by the underlying `EVAL` command.
Daniele Alessandri