coredata: Invalidate deps cache when changing wrap_mode option

Fixes: #8858

mesonbuild/coredata.py

@@ -634,6 +634,15 @@ class CoreData:
 
         if key.name == 'buildtype':
             self._set_others_from_buildtype(value)
+        elif key.name in {'wrap_mode', 'force_fallback_for'}:
+            # We could have the system dependency cached for a dependency that
+            # is now forced to use subproject fallback. We probably could have
+            # more fine grained cache invalidation, but better be safe.
+            self.clear_deps_cache()
+
+    def clear_deps_cache(self):
+        self.deps.host.clear()
+        self.deps.build.clear()
 
     def get_nondefault_buildtype_args(self):
         result= []

mesonbuild/mconf.py

@@ -85,8 +85,7 @@ class Conf:
             raise ConfException(f'Directory {build_dir} is neither a Meson build directory nor a project source directory.')
 
     def clear_cache(self):
-        self.coredata.deps.host.clear()
+        self.coredata.clear_deps_cache()
-        self.coredata.deps.build.clear()
 
     def set_options(self, options):
         self.coredata.set_options(options)