basic/env-util: drop the validation when deserializing environment

The environment variables we've serialized can quite possibly contain
characters outside the set allowed by env_assignment_is_valid(). In
fact, my environment seems to contain a couple of these:

  * TERMCAP set by screen contains a '\x7f' character
  * BASH_FUNC_module%% variable has a '%' character in name

Strict check of environment variables name and value certainly makes sense for
unit files, but not so much for deserialization of values we already had
in our environment.

src/basic/env-util.c

@@ -809,10 +809,5 @@ int deserialize_environment(char ***environment, const char *line) {
         if (r < 0)
                 return r;
 
-        if (!env_assignment_is_valid(uce)) {
-                free(uce);
-                return -EINVAL;
-        }
-
         return strv_env_replace(environment, uce);
 }

src/test/test-env-util.c

@@ -319,10 +319,10 @@ static void test_env_assignment_is_valid(void) {
 static void test_deserialize_environment(void) {
         _cleanup_strv_free_ char **env = strv_new("A=1", NULL);
 
-        assert_se(deserialize_environment(&env, "env=test") < 0);
         assert_se(deserialize_environment(&env, "env=B=2") >= 0);
+        assert_se(deserialize_environment(&env, "env=FOO%%=a\\177b\\nc\\td e") >= 0);
 
-        assert_se(strv_equal(env, STRV_MAKE("A=1", "B=2")));
+        assert_se(strv_equal(env, STRV_MAKE("A=1", "B=2", "FOO%%=a\177b\nc\td e")));
 }
 
 static void test_serialize_environment(void) {
@@ -334,6 +334,7 @@ static void test_serialize_environment(void) {
                                                   "B=2",
                                                   "C=ąęółń",
                                                   "D=D=a\\x0Ab",
+                                                  "FOO%%=a\177b\nc\td e",
                                                   NULL);
         _cleanup_strv_free_ char **env2 = NULL;