ECMA modes should not be saved by DECSC
From https://bugzilla.gnome.org/show_bug.cgi?id=731205#c1:
It seems to me that this list is exactly the list of variables that should be saved/restored on \e7 / \e8.
Unfortunately, that's not the case.
0001-emulation-ECMA-modes-should-not-be-saved-by-DECSC.patch