In the git configuration dialog, you have the option to prepend something to the PATH environment variable.
Suppose git or perl were in a directory that is not in the PATH variable or you wanted to use binaries from a different directory, then qt creator would probably not execute the (correct) binaries and that would be a problem, which can be solved by adding the directory to the beginning of the PATH variable (yay!)

However, if you didn't know how to solve the problem manually, then you would not be able to solve the problem inside creator either, because the caption "prepend to PATH" doesn't tell you, WHAT it does for you. It's what I call a backend-interface (as opposed to a user-interface), because it requires the user to adapt to the backend, instead of adapting the backend to the user.