> Pre-emptively I removed what I think are the offending lines in INSTALL.md in this commit: 3e05da6 . These are the only changes in that commit, so please just revert if I've moved a little too quickly!

Ah.  That was quick.  Quicker than my refresh.  I think we can put that paragraph back in, but just edit the math sentence to reflect that it is required rather than "might be" required in the future.