Thanks a lot, @Musca, for the downgrade hint! It worked great!
I didn't experience any failure due to cjs, @Harakiri. Actually, I have v.3 installed right now. I suppose I got lucky
They updated some more packages, but I don't think it's safe yet, since "cinnamon" package and many others are still at 2.8.7. Anyway, if I find any new error, I'll let you know.
The new packages are:
cinnamon-desktop-data 3.0.1-1
gir1.2-cinnamondesktop-3.03.0.1-1
libcinnamon-desktop43.0.1-1
And the whole bunch of risky packages, including cjs:
cinnamon-l10n3.0.0-1
cinnamon-session3.0.0-1
cinnamon-session-common3.0.0-1
gir1.2-cmenu-3.03.0.0-1
libcinnamon-menu-3.03.0.0-1
cinnamon-desktop-data3.0.1-1
gir1.2-cinnamondesktop-3.03.0.1-1
libcinnamon-desktop43.0.1-1
cjs3.0.1-1
libcjs03.0.1-1
cinnamon-core3
cinnamon-desktop-environment3
... and some "dev" packages