GitLab doesn't treat $ as literals in file content, which means that it
tries to do variable interpolation.
This is bad and annoying, because e.g. password hashes tend to contain $,
so they get variable-interpolated and thus corrupted.
Fix this by escaping $ on input to GitLab.
This is a file-type variable which contains the original mapping of
VARIABLE_NAME to VARIABLE_DATA.
This can be used to automatically repopulate a repository with
secrets that were originally taken from it and transmitted via
GitLab variables (i.e. out-of-band).
This allows me to use Supermicro's BMC, which appears to drop a
stunnel binary into /tmp and then execute it, which doesn't work
properly in Nix because nothing is where it is expected to be.
