compression 
 
Since uint3korr() may read 4 bytes depending on build flags and 
platform, allocate 1 extra "safety" byte in the network buffer 
for cases when uint3korr() in my_real_read() is called to read
last 3 bytes in the buffer. 
 
It is practically hard to construct a reliable and reasonably 
small test case for this bug as that would require constructing 
input stream such that a certain sequence of bytes in a 
compressed packet happens to be the last 3 bytes of the network 
buffer.