fix leak in module api rdb test
fix leak in module api rdb test

recently added more reads into that function, if a later read fails, i must
either free what's already allocated, or return the pointer so that the free
callback will release it.

soloestoy/redis,soloestoy/redis,charsyam/redis,soloestoy/redis,neomantra/redis,yossigo/redis,yossigo/redis,pmem/redis,oranagra/redis,oranagra/redis,charsyam/redis,oranagra/redis,oranagra/redis,yossigo/redis,ctripcorp/redis,charsyam/redis,antirez/redis,ofirluzon/redis,soloestoy/redis,neomantra/redis,PKRoma/redis,pmem/redis,PKRoma/redis,antirez/redis,neomantra/redis,PKRoma/redis,neomantra/redis,charsyam/redis,oranagra/redis,ctripcorp/redis,ofirluzon/redis,antirez/redis,ctripcorp/redis,pmem/redis,antirez/redis,ofirluzon/redis,pmem/redis,charsyam/redis,PKRoma/redis,ctripcorp/redis,neomantra/redis,ofirluzon/redis,yossigo/redis,ofirluzon/redis,yossigo/redis,soloestoy/redis,PKRoma/redis