Repository: dynaconf/dynaconf (python)

Issue:
Field '_bypass_evaluation' provided as part of the value of a setting
**Describe the bug**
When a BoxList containing a dictionary is created, when looking up the value of the BoxList, the field `_bypass_evaluation` is present in the dictionary.  This is unexpected.

**To Reproduce**
Steps to reproduce the behavior:

Using Dynaconf v3.2.0:

```
from dynaconf import Dynaconf

settings = Dynaconf()
settings.set("key", [{"d": "v"}])
settings.key
```
This provides the value of the key as:
`<BoxList: [{'d': 'v', '_bypass_evaluation': False}]>`

However, it is expected to be:
`<BoxList: [{'d': 'v'}]>`

**Executing under the following environment**
This happens in Ubuntu 20.04, python3, using  Dynaconf v3.2.0

**Proposed solution**
The following line:
```self._store._box_config["_bypass_evaluation"] = False```

at 
https://github.com/dynaconf/dynaconf/blob/678d29b7383f03934a47e21b1bcdf68946d5c501/dynaconf/base.py#L1174

can be replaced with:
```self._store._box_config.pop("_bypass_evaluation")```

This has the same result as setting it to False with the benefit that it is removed completely.


Pull request description:
Fix: unexpected _bypass_evaluation in BoxList
Fix #965 

Patch:
diff --git a/dynaconf/base.py b/dynaconf/base.py
index f481f31..c0c6c4e 100644
--- a/dynaconf/base.py
+++ b/dynaconf/base.py
@@ -1171,7 +1171,7 @@ class Settings:
         execute_module_hooks("post", self, env, silent=silent, key=key)
         execute_instance_hooks(self, "post", self._post_hooks)
 
-        self._store._box_config["_bypass_evaluation"] = False
+        self._store._box_config.pop("_bypass_evaluation")
 
     def pre_load(self, env, silent, key):
         """Do we have any file to pre-load before main settings file?"""


Test patch:
diff --git a/tests/test_base.py b/tests/test_base.py
index 9bd59d3..6e9fae8 100644
--- a/tests/test_base.py
+++ b/tests/test_base.py
@@ -1423,3 +1423,10 @@ def test_get_with_sysenv_fallback_local_overrides():
     assert settings.sysenv_fallback_for_dynaconf is True
     assert settings.get("another_test") == "ANOTHER_VALUE"
     assert not settings.get("another_test", sysenv_fallback=False)
+
+
+# issue #965
+def test_no_extra_values_in_nested_structure():
+    settings = Dynaconf()
+    settings.set("key", [{"d": "v"}])
+    assert settings.key == [{"d": "v"}]