Try using @TEMP@ instead of hard coding it.

CI/before_script.msvc.sh

@@ -422,7 +422,8 @@ fi
 			printf "Exists. "
 		elif [ -z $SKIP_EXTRACT ]; then
 			rm -rf Boost
-			"${DEPS}/boost-1.61.0-msvc${MSVC_YEAR}-win${BITS}.exe" //dir="$(echo $BOOST_SDK | sed s,/,\\\\,g)" //VERYSILENT //NORESTART //SUPPRESSMSGBOXES //LOG="boost_install.log"
+			"${DEPS}/boost-1.61.0-msvc${MSVC_YEAR}-win${BITS}.exe" //DIR="@TEMP@\boost" //VERYSILENT //NORESTART //SUPPRESSMSGBOXES //LOG="boost_install.log"			
+			mv @TEMP@/boost $BOOST_SDK
 		fi
 
 		add_cmake_opts -DBOOST_ROOT="$BOOST_SDK" \