Remove leftover references to files/pips/

The files/pips/* files were removed a while ago (replaced by
pip-requires in individual projects). So remove leftover code that was
dealing with that.

Change-Id: Id521a3365ab018193607389f022a25acddb49714
diff --git a/tools/build_ramdisk.sh b/tools/build_ramdisk.sh
index 8e2c0be..5ff05b0 100755
--- a/tools/build_ramdisk.sh
+++ b/tools/build_ramdisk.sh
@@ -108,7 +108,7 @@
     echo $NBD
 }
 
-# Prime image with as many apt/pips as we can
+# Prime image with as many apt as we can
 DEV_FILE=$CACHEDIR/$DIST_NAME-dev.img
 DEV_FILE_TMP=`mktemp $DEV_FILE.XXXXXX`
 if [ ! -r $DEV_FILE ]; then
@@ -121,7 +121,6 @@
 
     chroot $MNTDIR apt-get install -y --download-only `cat files/apts/* | grep NOPRIME | cut -d\# -f1`
     chroot $MNTDIR apt-get install -y --force-yes `cat files/apts/* | grep -v NOPRIME | cut -d\# -f1`
-    chroot $MNTDIR pip install `cat files/pips/*`
 
     # Create a stack user that is a member of the libvirtd group so that stack
     # is able to interact with libvirt.