UGENE Genome Aligner can't be canceled in some cases

Scenario to reproduce:

1. Select {Tools -> NGS data analysis -> Map reads to reference}

   in the main menu.
   Expected state: "Align Sequencing Reads" dialog appeared.

2. Select "UGENE Genome Aligner" method in the dialog;
   Set reference sequence: "_common_data/bwa/NC_000021.gbk.fa";
   Short reads: "_common_data/bwa/nrsf-chr21.fastq";
   Press "Start".
3. Wait until ShortReadAlignerCPU tasks are on 25% and cancel the top task
   Current state: only one ShortReadAlignerCPU task is canceled, other still have "running" state and wait for something.