Working on multiple versions of Qt from git without cloning every version

commands.sh

# This script assumes that you want to work on qt3d, qtquickcontrols (1 and 2), datavis3d and qtcharts. 
# Replace the modules below if you need others.

# Clone dev version
mkdir dev
cd dev # ./dev
git clone git://code.qt.io/qt/qt5.git
cd qt5 # ./dev/qt5
git checkout dev
perl init-repository --codereview-username yourusername -branch dev --module-subset=default,qtcharts,qtdatavis3d,-qtwebkit,-qtwebkit-examples,-qtwebengine,-qtwebview
cd ..  # ./dev

# Build debug and release versions
mkdir build-debug
cd build-debug # ./dev/build-debug
../qt5/configure -developer-build -opensource -nomake tests -nomake examples -confirm-license -debug
make module-qt3d module-qtquickcontrols module-qtquickcontrols2 module-qtdatavis3d module-qtcharts -j4
cd .. # ./dev/
mkdir build-release
cd build-release # ./dev/build-release
../qt5/configure -developer-build -opensource -nomake tests -nomake examples -confirm-license -release
make module-qt3d module-qtquickcontrols module-qtquickcontrols2 module-qtdatavis3d module-qtcharts -j4
cd .. # ./dev/

cd .. # ./
# Clone 5.9, but reuse repos from dev (using --alternates)
mkdir 5.9
cd 5.9 # ./5.9
git clone git://code.qt.io/qt/qt5.git 
cd qt5 # ./5.9/qt5
git checkout 5.9
perl init-repository --codereview-username yourusername -branch 5.9 --module-subset=default,qtcharts,qtdatavis3d,-qtwebkit,-qtwebkit-examples,-qtwebengine,-qtwebview --alternates=../../dev/qt5
cd .. # ./5.9/

# like above: mkdir build-debug, mkdir build-release, configure, and make