There seems to be multiple forms of $\ce{HI}$ used to cleave epoxides:
conc. $\ce{HI}$, anhydrous $\ce{HI}$, cold $\ce{HI}$, hot $\ce{HI}$, cold conc. $\ce{HI}$, hot conc. $\ce{HI}$, etc.
So, does concentration of $\ce{HI}$ and temperature have any significance in determining the product?