Wrong output of dropTag in SPLiT-seq mode

[realzhang]

I found dropTag modified the original sequence of fastq read. Some read are wrongly assigned by sequence of others. There could be some error in the order of processing.

[realzhang]

For example,
Original fq: (SPLiT-seq)

@seq1
AAA
@seq2
**TTT**
@seq3
CCC

After tagging:

@seq1_bc3bc2bc1_UMI
AAA
@seq2_bc3bc2bc1_UMI
**CCC**
@seq3_bc3bc2bc1_UMI
CCC