Lua environmental differences

[bmerry]

The Lua scripting support (EVAL) does not perfectly emulate the environment available to a real redis script. Some known differences are:

• Libraries such as cjson are not loaded
• Setting of global variables is only checked each time a redis function is called, rather than being enforced by a metatable.
• dofile and readfile are not disabled.
• Various functions on the redis object are not implemented e.g. redis.sha1hex, redis.log
• It doesn't prevent mutating commands after a random command (this will be a major task since it requires knowing which commands are mutating and/or random).
• The random seed might not be reset with every script (untested)

For more details see the redis documentation and [implementation(https://github.com/antirez/redis/blob/32ac4c64baf00747da1acc0cc61ee236922e2dcf/src/scripting.c#L867-L885).

[bmerry]

Closing because development has moved back to fakeredis.