chore(gevent): disable gevent hub reinit (backport #4252) (#4267)

This is an automatic backport of pull request #4252 done by [Mergify](https://mergify.com).


---


<details>
<summary>Mergify commands and options</summary>

<br />

More conditions and actions can be found in the [documentation](https://docs.mergify.com/).

You can also trigger Mergify actions by commenting on this pull request:

- `@Mergifyio refresh` will re-evaluate the rules
- `@Mergifyio rebase` will rebase this PR on its base branch
- `@Mergifyio update` will merge the base branch into this PR
- `@Mergifyio backport <destination>` will backport this PR on `<destination>` branch

Additionally, on Mergify [dashboard](https://dashboard.mergify.com/) you can:

- look at your merge queues
- generate the Mergify configuration with the config editor.

Finally, you can contact us on https://mergify.com
</details>

Author: mergify[bot]

ddtrace/internal/forksafe.py

@@ -8,6 +8,7 @@
 import weakref
 
 from ddtrace.internal.module import ModuleWatchdog
+from ddtrace.internal.utils.formats import asbool
 from ddtrace.vendor import wrapt
 
 
@@ -39,7 +40,8 @@ def wrapped_reinit(f, args, kwargs):
     wrap(module.reinit, wrapped_reinit)
 
 
-ModuleWatchdog.register_module_hook("gevent.hub", patch_gevent_hub_reinit)
+if asbool(os.getenv("_DD_TRACE_GEVENT_HUB_PATCHED", default=False)):
+    ModuleWatchdog.register_module_hook("gevent.hub", patch_gevent_hub_reinit)
 
 
 def ddtrace_after_in_child():

tests/internal/test_forksafe.py

@@ -291,6 +291,7 @@ def fn():
 @pytest.mark.subprocess(
     out="" if (3,) < sys.version_info < (3, 7) else ("CTCTCT" if sys.platform == "darwin" else "CCCTTT"),
     err=None,
+    env=dict(_DD_TRACE_GEVENT_HUB_PATCHED="true"),
 )
 def test_gevent_reinit_patch():
     import os