You probably did the same thing I did. Hit the "Download" button to download Qt5 source.
# ./configure -developer-build -opensourceSolution: use git to pull Qt5 so you'll have init-repository
/.../qt5/qtbase/configure not found. Did you forget to run "init-repository"?
-bash: init-repository: command not found
# ls qtbase
# git clone git://gitorious.org/qt/qt5.git qt5
# ./configure -developer-build -opensource