prevent potential (but harmless) Python notice during builds)

CHANGELOG.md

@@ -1,5 +1,11 @@
 # heroku-buildpack-php CHANGELOG
 
+## v75 (2015-08-21)
+
+### FIX
+
+- Prevent potential (benign) Python notice during builds
+
 ## v74 (2015-08-21)
 
 ### FIX

bin/compile

@@ -131,7 +131,7 @@ print json.dumps(ret)
 Run 'composer update' to have it re-generated by Composer."
 
     # warn if minimum-stability is set to non-stable (regardless of whether prefer-stable is used)
-    if echo -n "$solver_payload" | python -c 'import sys, json; p = json.load(sys.stdin); sys.exit(p["lock"]["minimum-stability"] == "stable");'; then
+    if echo -n "$solver_payload" | python -c 'import sys, json; p = json.load(sys.stdin); sys.exit(p["lock"] == None or p["lock"]["minimum-stability"] == "stable");' 2> /dev/null; then
         warning "Your 'composer.json' contains a non-'stable' setting
 for 'minimum-stability'. This may cause the installation of
 unstable versions of runtimes and extensions during this deploy.