[daemon] Don't do updates of builtins modules (#8777)

We hit a bug internally involving this. I'm going to put a bit more
effort into tracking those in case they are more general, but in
general, nothing good can come of it, I think.

mypy/server/update.py

@@ -137,7 +137,9 @@
 from mypy.server.astdiff import (
     snapshot_symbol_table, compare_symbol_table_snapshots, SnapshotItem
 )
-from mypy.semanal_main import semantic_analysis_for_scc, semantic_analysis_for_targets
+from mypy.semanal_main import (
+    semantic_analysis_for_scc, semantic_analysis_for_targets, core_modules
+)
 from mypy.server.astmerge import merge_asts
 from mypy.server.aststrip import strip_target, SavedAttributes
 from mypy.server.deps import get_dependencies_of_target, merge_dependencies
@@ -148,6 +150,8 @@
 
 MAX_ITER = 1000  # type: Final
 
+SENSITIVE_INTERNAL_MODULES = tuple(core_modules) + ("mypy_extensions", "typing_extensions")
+
 
 class FineGrainedBuildManager:
     def __init__(self, result: BuildResult) -> None:
@@ -342,6 +346,12 @@ def update_module(self,
         self.manager.log_fine_grained('--- update single %r ---' % module)
         self.updated_modules.append(module)
 
+        # builtins and friends could potentially get triggered because
+        # of protocol stuff, but nothing good could possibly come from
+        # actually updating them.
+        if module in SENSITIVE_INTERNAL_MODULES:
+            return [], (module, path), None
+
         manager = self.manager
         previous_modules = self.previous_modules
         graph = self.graph