cvs.eclass is the only scm eclass which ignores ESCM_OFFLINE (bzr.eclass, git.eclass, mercurial.eclass, subversion.eclass all do). In addition, ECVS_OFFLINE has a slightly different syntax than the other offline variables (EBZR_OFFLINE, EGIT_OFFLINE, EHG_OFFLINE, ESVN_OFFLINE): While the others are active if they are just nonempty, ECVS_OFFLINE only becomes active if it is "1". Both issues can be solved simultaneously by modifying one line.
Created attachment 222021 [details, diff] Treat CVS_OFFLINE/ESCM_OFFLINE analogously to the other scm eclasses
Thanks for your proposed patch -- assigning to the eclass maintainer.
should be all set now ... thanks http://sources.gentoo.org/eclass/cvs.eclass?r1=1.71&r2=1.72