software/slapos-sr-testing: prevent softwares from using system python

Put broken python interpreters in path so that fail if they try to use
system python

software/slapos-sr-testing/software.cfg

@@ -22,6 +22,7 @@ extends =
 
 parts =
   eggs/scripts
+  python2.7-disabled
   slapos-cookbook
   template
 
@@ -251,6 +252,26 @@ branch = master
 egg = slapos.core
 setup = ${slapos.core-repository:location}
 
+[python2.7-disabled]
+# An "intentionally broken" python2 command that should catch
+# accidental usage of things like #!/usr/bin/env python2
+recipe = zc.recipe.egg
+# we need an egg to generate a script, use the one from this part's recipe
+eggs = ${:recipe}
+interpreter = python2.7
+entry-points =
+  python=${:eggs}:ignored
+  python2=${:eggs}:ignored
+  python2.7=${:eggs}:ignored
+scripts =
+  python
+  python2
+  python2.7
+initialization =
+  import sys
+  print("Error: attempt to use system python2", file=sys.stderr)
+  sys.exit(2)
+
 [python-interpreter]
 eggs +=
   ${lxml-python:egg}