If we check out and build a certain revision of a dependency in a branch and
switch to another that requires a different revision and then switch back,
the previous approach installed the wrong revision as it would incorrectly
assume the required revision was already built and ready to install.
The tkm scenarios recently failed due to a segmentation fault on my host
because I had an old build of the tkm library already built in the build
directory. Because the stamp file was not versioned the new release was
never checked out or built and charon-tkm was linked against the old
version causing a segmentation fault during key derivation.
