Make ALTER ROLE edgedb refer to admin if edgedb doesn't exist

This makes mirrors the logic for logins and avoid breaking setup
scripts, such as those in our client test suites and possibly in some
user suites.

Follow-up to #8010.
Makes geldata/gel-python#550 unnecessary.

edb/schema/roles.py

@@ -18,7 +18,7 @@
 
 
 from __future__ import annotations
-from typing import Optional, Type, List, TYPE_CHECKING
+from typing import Optional, Type, List, Union, overload, TYPE_CHECKING
 
 from edgedb import scram
 
@@ -30,6 +30,7 @@
 from . import annos as s_anno
 from . import delta as sd
 from . import inheriting
+from . import name as sn
 from . import objects as so
 from . import utils
 
@@ -195,6 +196,60 @@ class RenameRole(RoleCommand, sd.RenameObject[Role]):
 class AlterRole(RoleCommand, inheriting.AlterInheritingObject[Role]):
     astnode = qlast.AlterRole
 
+    @overload
+    def get_object(
+        self,
+        schema: s_schema.Schema,
+        context: sd.CommandContext,
+        *,
+        name: Optional[sn.Name] = None,
+        default: Union[Role, so.NoDefaultT] = so.NoDefault,
+        sourcectx: Optional[qlast.Span] = None,
+    ) -> Role:
+        ...
+
+    @overload
+    def get_object(
+        self,
+        schema: s_schema.Schema,
+        context: sd.CommandContext,
+        *,
+        name: Optional[sn.Name] = None,
+        default: None = None,
+        sourcectx: Optional[qlast.Span] = None,
+    ) -> Optional[Role]:
+        ...
+
+    def get_object(
+        self,
+        schema: s_schema.Schema,
+        context: sd.CommandContext,
+        *,
+        name: Optional[sn.Name] = None,
+        default: Union[Role, so.NoDefaultT, None] = so.NoDefault,
+        sourcectx: Optional[qlast.Span] = None,
+    ) -> Optional[Role]:
+        # On an ALTER ROLE edgedb, if 'edgedb' doesn't exist, fall
+        # back to 'admin'. This mirrors what we do for login and
+        # avoids breaking setup scripts.
+        if name is None and str(self.classname) == 'edgedb':
+            try:
+                return super().get_object(
+                    schema,
+                    context,
+                    sourcectx=sourcectx,
+                )
+            except errors.InvalidReferenceError:
+                name = sn.UnqualName('admin')
+
+        return super().get_object(
+            schema,
+            context,
+            name=name,
+            default=default,
+            sourcectx=sourcectx,
+        )
+
     @classmethod
     def _cmd_tree_from_ast(
         cls,

tests/test_server_ops.py

@@ -419,6 +419,19 @@ async def test_server_only_bootstraps_once(self):
                 finally:
                     await con.aclose()
 
+    async def test_server_alter_role_fallback(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            async with tb.start_edgedb_server(
+                data_dir=temp_dir,
+                default_auth_method=args.ServerAuthMethod.Scram,
+                bootstrap_command='ALTER ROLE edgedb SET password := "first";'
+            ) as sd:
+                con = await sd.connect(password='first')
+                try:
+                    await con.query_single('SELECT 1')
+                finally:
+                    await con.aclose()
+
     async def test_server_ops_bogus_bind_addr_in_mix(self):
         async with tb.start_edgedb_server(
             bind_addrs=('host.invalid', '127.0.0.1',),