Fusion with frameshift in donor and variant right after accepter breakpoint

[zhuchcn]

Fuzz test caught an edge case when there is a frameshift in the donor transcript and a variant right after the accetper breakpoint in the accepter transcript. The DNA graph is like below. The node C in reading frame 2 got skipped so fit_into_codon terminated early leaving nodes not being multiple of three.

                                  |                G
                                  |               / \
0-  ATACAC..TGAGGG-TAGAGGGAAATGGG-ATAGCC..CCAGAT-C-T-TGTCTC..ACATCC
                  \
                   T-------------
                                 \                 G
                                  |               / \
1-  TACACT..TGAGGG-TAGAGGGAAATGGG-ATAGCC..CCAGAT-C-T-TGTCTC..ACATCC

                                    G
                                   / \
2-  ACACTC..TGAGGG-TAGAGG..CCAGAT-C-T-TGTCTC..ACATCC
                  \
                   T------------
                                \
``