serf: requires clt for now
subversion 1.8.1

Closes #21425.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
bison 3.0

Closes #21444.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
pip 1.4

Closes #21411.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>