Prepending bytearray: TypeError: an integer is required

Question

I have two bytearrays:

ba1 = bytearray(b'abcdefg')
ba2 = bytearray(b'X')

How can I insert ("prepend") ba2 in ba1?

I tried to do:

ba1.insert(0, ba2)

But this doesn't seem to be correct.

Of course I could do following:

ba2.extend(ba1)
ba1 = ba2

But what if ba1 is very big? Would this mean unnecessary coping of the whole ba1? Is this memory-efficient?

How can I prepend a bytearray?