1377-Blacklist dependencies in git

now ensure_dependencies.py add dependecies to .git/info/exclude. 
Please write any non-trivial intermediate values into explicit variables before using them any further. While this increases the amount of code-lines, it also increases the readability. Even more important: It eases debugging (in any language!), irregardless whether one wants to manually store/dump the values or use a debugger to set some stop point.