Use 'which pip' rather than /usr/bin/pip

Bug 1095472: Bugfix to use 'which pip' rather than assume pip always lives in /usr/bin

Change-Id: I0cc8a5e35306372653c3c27da9504c64e39d56dd
diff --git a/functions b/functions
index 23aee93..bb03c55 100644
--- a/functions
+++ b/functions
@@ -1146,9 +1146,9 @@
 # get_pip_command
 function get_pip_command() {
     if is_fedora; then
-        echo "/usr/bin/pip-python"
+        which pip-python
     else
-        echo "/usr/bin/pip"
+        which pip
     fi
 }