run-postinsts: Replace pi_dir variable test

Since commit 5159ddcb62 string length test
performed against pi_dir has effectively never been able to succeed.

Change this to rather test if pi_dir is not an existing directory. By
doing we remove the chance of seeing the following console error message
during first boot to a pristine rootfs:

  'ls: /etc/ipk-postinsts: No such file or directory'

(From OE-Core rev: b1600ec8991dfbd3b73d209b9c620a171c5b13c4)

Signed-off-by: Niko Mauno <niko.mauno@iki.fi>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/run-postinsts/run-postinsts/run-postinsts

@@ -43,7 +43,7 @@ remove_rcsd_link () {
 	fi
 }
 
-if [ -z "$pi_dir" ]; then
+if ! [ -d $pi_dir ]; then
 	remove_rcsd_link
 	exit 0
 fi

meta/recipes-devtools/run-postinsts/run-postinsts_1.0.bb

@@ -1,6 +1,6 @@
 SUMMARY = "Runs postinstall scripts on first boot of the target device"
 SECTION = "devel"
-PR = "r9"
+PR = "r10"
 LICENSE = "MIT"
 LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"