+ # Leave any existing symlink alone, if it already points to the source,
+ # so that broken build tools that care about symlink times
+ # aren't confused into doing unnecessary builds. Conversely, if the
+ # existing symlink's time stamp is older than the source, make it afresh,
+ # so that broken tools aren't confused into skipping needed builds. See
+ # <http://lists.gnu.org/archive/html/bug-gnulib/2011-05/msg00326.html>.