Unreferences the bytes, and returns a new mutable
the same byte data.
As an optimization, the byte data is transferred to the array without copying
if this was the last reference to bytes and bytes was created with
g_bytes_new_take() or g_byte_array_free_to_bytes(). In all
other cases the data is copied.
Do not use it if
bytes contains more than
GByteArray stores the length of its data in #guint, which
may be shorter than #gsize, that
bytes is using.