  We study the effect of commensurability (integer filling factor) on the
superfluid (SF) - Bose-glass (BG) transition in a one-dimensional disordered
system in the limit of weak disorder, when the effect is most pronounced and,
on the other hand, may be traced via the renormalization-group analysis. The
equation for the SF-BG phase boundary demonstrating the effect of
disorder-stimulated superfluidity implies that the strength of disorder
sufficient to restore superfluidity from Mott insulator (MI) is much larger
than that enough to turn MI into BG. Thus we provide an explicit proof of the
fact that at arbitrarily small disorder the SF and MI phases are always
separated by BG.
