Running scripts in wrong order results in "broken" directory

[mcclure]

Small heads up. The instructions clearly state to run updatelibs.sh followed by buildlibs.sh. But lets say someone just charged ahead and didn't read the instructions, and ran buildlibs.sh without running updatelibs first. Their fnalibs-apple-builder checkout is now "broken" and neither updatelibs.sh nor buildlibs.sh will be able to work (except for, some reason, libtheora) without doing a git clean -xffd. Once in this state, they will not get helpful error messages. I think that this is happening because buildlibs.sh, if run first, creates a (for example) empty SDL2/ directory, which will prevent updatelibs from being able to clone a directory at that path.

I recommend either putting check(s) in buildlibs.sh to prevent it doing anything if it detects that the checkout has not already occurred (for example, aborting or skipping targets if the SDL/ or other expected directories are not present, or adding a warning note in the README along the lines of "if buildlibs.sh says CMakeLists.txt is not found, try doing a git clean -xffd and starting over." (Sorry, I don't have a copy of the original error message.)