Fix #1698 (http://svn.boost.org/trac/boost/ticket/1698).

    * build/virtual-target.jam (register): Ignore
    differences in incidental dependency features.


[SVN r43721]

tools/build

@@ -1 +1 @@
-Subproject commit b553af4b1efbb8b5de94deb722af0f2b4adbb6e6
+Subproject commit dfe0e931f8649a96831bd24f42c5f53daf1012e3