Fix lib_installed_from_git

In commit f0cd9a8b08d92524fc8e2c3f05d08cdebc638e2a we changed to
use column format, but it checks for zero length string and
check_libs_from_git fails.

Change-Id: I97b52b80efb33749647229a55147a08afa112dd2
diff --git a/inc/python b/inc/python
index 9a65bfe..9f56ec5 100644
--- a/inc/python
+++ b/inc/python
@@ -419,7 +419,7 @@
     #  bashate 0.5.2.dev19 /tmp/env/src/bashate
     # Thus we check the third column to see if we're installed from
     # some local place.
-    [[ -z $(pip list --format=columns 2>/dev/null | awk "/^$name/ {print \$3}") ]]
+    [[ -n $(pip list --format=columns 2>/dev/null | awk "/^$name/ {print \$3}") ]]
 }
 
 # check that everything that's in LIBS_FROM_GIT was actually installed