this is very strange. It looks like there's an extra module (that you shouldn't be rebuilding, anyway) which tries to find an old version of GNU Radio. Can you tell us which module that is?
You should realize what your doing here: you download the build-gnuradio script anew, and then call it two times... that's one download and one execution too many.
The pupose of the build-gnuradio script is to fetch the source code and install all requirement, and in the end build GNU Radio and install it. Since you're modifying the source code, this might *not* be what you want.
What you should be doing is going into your existing gnuradio/build directory, and do a "make -j3"[1], "sudo make install". This should be faster. Please check that your modifications are still around before, build-gnuradio might have overwritten them.
In the other thread you asked what you can do to understand the C++ code; my suggestion here is going through
http://gnuradio.org/redmine/projects/gnuradio/wiki/Tutorials , especially the "core concepts" and the "developing out-of-tree modules" tutorial, as well as "how to debug". I think the problem lies usually less in the C++ code but in the complexity brought on by a complex framework such as GNU Radio and by a complex task such as doing OFDM synchronization in software -- it's very important you get a feeling of what the system is doing (and what you are doing with the system) before trying to understand the C++ code in isolation.
Hope that helped a little,
Greetings,
Marcus
[1] or something, the -j parameters tells make how many things to do in parallel. As a rule of thumb: Number of CPU cores + 1