Is there any workaround other than locally revert Julien's commit?
That's not a "workaround" since your fonts would all be broken.
Maybe install TeXlive2013 to a local tree and update to the newest
version using tlmgr?
It's not necessary to downlaod the whole TeXLive; it is fully
sufficient to download a new mpost binary from the TeXLive's SVN:
http://www.tug.org/svn/texlive/trunk/Master/bin/
Note, however, that you must *replace* the old binary, this is, the
new binary must put into the same directory as the old binary was.