[Boost-build] Percent signs in Windows paths

From: Chambers, Matthew (matt.chambers42_at_[hidden])
Date: 2020-09-10 14:34:15

I'm trying to pass a filename with a % in it to a run target and running into an issue with the % disappearing because of Windows cmd 
processing. If I double up the % in the run target, just like I would in a Windows batch file, it works. Should Boost.Build handle this 
automatically?