My system is running from Tumbleweed repos and I am trying to build a package for this repo. When i run command

osc build openSUSE_Tumbleweed

i got this

Building libtorrent.spec for openSUSE_Tumbleweed/x86_64
Getting buildinfo from server and store to /home/maksym/projects/home:elysium31/home:elysium31:branches:filesharing/libtorrent/.osc/_buildinfo-openSUSE_Tum
Getting buildconfig from server and store to /home/maksym/projects/home:elysium31/home:elysium31:branches:filesharing/libtorrent/.osc/_buildconfig-openSUSE
Updating cache of required packages

The build root needs packages from project 'openSUSE:Factory'.
Note that malicious packages can compromise the build result or even your system.
Would you like to ...
0 - quit (default)
1 - always trust packages from 'openSUSE:Factory'
2 - trust packages just this time

It is going to install some packages from Factory.
Is there any way to build on installed packages (Tumbleweed)? Should i generate a buildinfo against Tumblweed somehow?