It will still give you red lights inside!
Did this to me once on a P2v, when visiting friends for graduation, wanted some aerials of her graduating, but small airport very close by, so was a NO GO for me! But you can give it a try, worst that will happen is NFZ WARNING! Remember without gps lock indoors, you will be flying ATTI mode, so you will be in control, with little to no help from gps! Unless you are experienced at flying ATTI in closed quarters, and without gps help, it might not be the greatest of ideas!
If you feel confident enough, to do so, than give her a try, at least you'll know FOR SURE!
( hint: try with props off first, see if she will engage, and stay engaged without NFZ interference, and if all is good, you might get away with it? )
Either way, let us know how it goes? I'd be interested to know if it works or not?
J Dot