utils: orig_environ cleans LD_LIBRARY_PATH

LD_LIBRARY_PATH is set earlier than some of the other environment
variables like PATH or PYTHONPATH, so trying to save a clean version in
snapcraft is not viable.  Remove it here.

subiquitycore/tests/test_utils.py

@@ -40,10 +40,16 @@ class TestOrigEnviron(SubiTestCase):
         expected = {}
         self.assertEqual(expected, orig_environ(env))
 
+    def test_no_ld_library_path(self):
+        env = {'LD_LIBRARY_PATH': 'a'}
+        expected = {}
+        self.assertEqual(expected, orig_environ(env))
+
     def test_practical(self):
         snap = '/snap/subiquity/1234'
         env = {
             'TERM': 'linux',
+            'LD_LIBRARY_PATH': '/var/lib/snapd/lib/gl',
             'PYTHONIOENCODING_ORIG': '',
             'PYTHONIOENCODING': 'utf-8',
             'SUBIQUITY_ROOT_ORIG': '',

subiquitycore/utils.py

@@ -36,6 +36,8 @@ def _clean_env(env, *, locale=True):
 
 
 def orig_environ(env):
+    """Generate an environment dict that is suitable for use for running
+    programs that live outside the snap."""
     if env is None:
         env = os.environ
     ret = env.copy()
@@ -47,6 +49,7 @@ def orig_environ(env):
             else:
                 del ret[key_to_restore]
             del ret[key]
+    ret.pop('LD_LIBRARY_PATH', None)
     return ret