avoid resizing buffer - #3253

b = bytearray(10)  # LimitedStream.readinto(target)
remaining = 5  # 5 remaining bytes to read, smaller than target
temp_b = bytearray(5)  # buffer that only fits remaining bytes
out_size = 3  # internal stream.readinto(temp) only read 3 bytes instead of the remaining 5

b[:out_size] = temp_b  # assigning 5 byte buffer to 3 byte slice
# b is now 12 bytes to accommodate the 2 extra bytes

# fix:
b[:out_size] = temp_b[:out_size]  # assign same number of bytes as target slice