[REG: 6.3 -> 6.4] QtSynchronizeRepo.cmake does not clone missing dependencies

1. Clone Qt's super repo.

   git clone https://codereview.qt-project.org/qt/qt5.git
   

2. Copy the cmake scripts to your working directory so you can use them for separate clones.

   cp -r qt5/cmake/ .
   

3. Clone qtsvg.

   git clone https://codereview.qt-project.org/qt/qtsvg.git
   

4. Try using QtSynchronizeRepo for checking out qtsvg's dependencies.

   cmake -DSYNC_TO_MODULE=qtsvg -DSYNC_TO_BRANCH=dev -P cmake/QtSynchronizeRepo.cmake
   

   The script will not check out qtbase, qtsvg's only dependency:

   Checking 'qtsvg' out to revision 'dev'
   

Before 8a94d1e was merged, this worked fine:

Checking 'qtsvg' out to revision 'dev'
Cloning qtbase from https://codereview.qt-project.org/qt/qtbase.git
Checking 'qtbase' out to revision 'de6ced66920600e659dbaa2509526a3bcb0b3360'