hooks: avoid mutating self in call_extra

call_extra previously worked by saving the exiting hookimpls, call
self._add_hookimpl() with all the extras, doing the call then restoring
the old hookimpls.

This is mostly fine but prevents the fields from being made Final, and
probably has some reentrancy issues, so I think it's much better to
avoid such tricks.

Author: bluetech

src/pluggy/_hooks.py

@@ -407,22 +407,24 @@ def call_extra(
             not self.is_historic()
         ), "Cannot directly call a historic hook - use call_historic instead."
         self._verify_all_args_are_provided(kwargs)
-        old = list(self._nonwrappers), list(self._wrappers)
+        opts: "_HookImplOpts" = {
+            "hookwrapper": False,
+            "optionalhook": False,
+            "trylast": False,
+            "tryfirst": False,
+            "specname": None,
+        }
+        hookimpls = self.get_hookimpls()
         for method in methods:
-            opts: "_HookImplOpts" = {
-                "hookwrapper": False,
-                "optionalhook": False,
-                "trylast": False,
-                "tryfirst": False,
-                "specname": None,
-            }
             hookimpl = HookImpl(None, "<temp>", method, opts)
-            self._add_hookimpl(hookimpl)
+            # Find last non-tryfirst nonwrapper method.
+            i = len(hookimpls) - 1
+            until = len(self._nonwrappers)
+            while i >= until and hookimpls[i].tryfirst:
+                i -= 1
+            hookimpls.insert(i + 1, hookimpl)
         firstresult = self.spec.opts.get("firstresult", False) if self.spec else False
-        try:
-            return self._hookexec(self.name, self.get_hookimpls(), kwargs, firstresult)
-        finally:
-            self._nonwrappers, self._wrappers = old
+        return self._hookexec(self.name, hookimpls, kwargs, firstresult)
 
     def _maybe_apply_history(self, method: "HookImpl") -> None:
         """Apply call history to a new hookimpl if it is marked as historic."""