Flash test fix (#4650)
Flash test fix (#4650)

* flash: fix test for multiple threads used

order of the written reads may differ

* flash: add expect_num_outputs
nsoranzo/tools-iuc,nsoranzo/tools-iuc,pavanvidem/tools-iuc,nsoranzo/tools-iuc,galaxyproject/tools-iuc,pavanvidem/tools-iuc,jj-umn/tools-iuc,gregvonkuster/tools-iuc,loraine-gueguen/tools-iuc,jj-umn/tools-iuc,pavanvidem/tools-iuc,nsoranzo/tools-iuc,galaxyproject/tools-iuc,loraine-gueguen/tools-iuc,galaxyproject/tools-iuc,jj-umn/tools-iuc,galaxyproject/tools-iuc,pavanvidem/tools-iuc,loraine-gueguen/tools-iuc,pavanvidem/tools-iuc,loraine-gueguen/tools-iuc,gregvonkuster/tools-iuc,galaxyproject/tools-iuc,nsoranzo/tools-iuc,gregvonkuster/tools-iuc,gregvonkuster/tools-iuc,gregvonkuster/tools-iuc,gregvonkuster/tools-iuc,galaxyproject/tools-iuc,nsoranzo/tools-iuc,jj-umn/tools-iuc,nsoranzo/tools-iuc,galaxyproject/tools-iuc,pavanvidem/tools-iuc,jj-umn/tools-iuc,gregvonkuster/tools-iuc,loraine-gueguen/tools-iuc,jj-umn/tools-iuc,jj-umn/tools-iuc,loraine-gueguen/tools-iuc,pavanvidem/tools-iuc,loraine-gueguen/tools-iuc