I didn’t think this was even possible, but I did it:
~/cmdstan/stan/lib/stan_math(develop)$ git commit -a -m "refactor, doc, replace const T with const T&" [develop 4d7a8f2] refactor, doc, replace const T with const T& 29 files changed, 215 insertions(+), 277 deletions(-) rewrite stan/math/prim/mat/err/check_ldlt_factor.hpp (67%) rewrite stan/math/prim/mat/fun/rank.hpp (76%) ~/cmdstan/stan/lib/stan_math(develop)$ git push Counting objects: 85, done. Delta compression using up to 8 threads. Compressing objects: 100% (47/47), done. Writing objects: 100% (47/47), 10.27 KiB, done. Total 47 (delta 32), reused 0 (delta 0) remote: Resolving deltas: 100% (32/32), completed with 30 local objects. To https://github.com/stan-dev/math.git 6f02a99..4d7a8f2 develop -> develop
Now the question is how to I undo that magic?