fix: fix py27 RAISE_VARARGS_A cause pycdc crash

[plusls]

In python 2.7, some times have JUMP_FORWARD after RAISE_VARARGS, and sometimes not, we should check if we are in the end of if block

JUMP_FORWARD example:

                    Object Name: _check_closed
                    Arg Count: 1
                    Locals: 1
                    Stack Size: 2
                    Flags: 0x00000043 (CO_OPTIMIZED | CO_NEWLOCALS | CO_NOFREE)
                    [Names]
                        'closed'
                        'ValueError'
                    [Var Names]
                        'self'
                    [Free Vars]
                    [Cell Vars]
                    [Constants]
                        'Raises a ValueError if the underlying file object has been closed.\n\n        '
                        'I/O operation on closed file.'
                        None
                    [Disassembly]
                        0       LOAD_FAST                       0: self
                        3       LOAD_ATTR                       0: closed
                        6       POP_JUMP_IF_FALSE               24
                        9       LOAD_GLOBAL                     1: ValueError
                        12      LOAD_CONST                      1: 'I/O operation on closed file.'
                        15      CALL_FUNCTION                   1
                        18      RAISE_VARARGS                   1
                        21      JUMP_FORWARD                    0 (to 24)
                        24      LOAD_CONST                      2: None

no JUMP_FORWARD example:

                        404     STORE_ATTR                      25: compress
                        407     JUMP_FORWARD                    17 (to 427)
                        410     LOAD_GLOBAL                     26: IOError
                        413     LOAD_CONST                      14: 'Mode '
                        416     LOAD_FAST                       2: mode
                        419     BINARY_ADD                      
                        420     LOAD_CONST                      15: ' not supported'
                        423     BINARY_ADD                      
                        424     RAISE_VARARGS                   2
                        427     LOAD_FAST                       4: fileobj
                        430     LOAD_FAST                       0: self
                        433     STORE_ATTR                      27: fileobj
                        436     LOAD_CONST                      8: 0

This crash cause by https://github.com/zrax/pycdc/pull/561

[whoami730]

Please avoid force pushes/rebases. Old comments are marked as outdated otherwise and makes it harder for reviewers to keep track of what changes have been reviewed and what haven't.