I used "use provided bridges" option for obfs3 in TBB 3.6. When I got TBB 3.6.2, I didn't copy over torrc from old directory, I thought it might get new set of "provided bridges", but when I opened and read TBB 3.6.2's torrc file, it has the same set of obfs3 bridges as in the TBB 3.6's torrc.
So now I wish to know how TBB gets its list of "provided bridges"? Is it added with the downloaded TBB itself? Then, everyone will be able to see the bridges from sourcecode and add it to their tor nodes blocklist?