Do not read build string without first checking XNCP feature bitmap (#660)

* Do not read build string without first checking XNCP feature bitmap

* Fix unit test

Author: puddly

bellows/ezsp/__init__.py

@@ -362,11 +362,11 @@ async def get_board_info(
             patch, ver_info_bytes = t.uint8_t.deserialize(ver_info_bytes)
             special, ver_info_bytes = t.uint8_t.deserialize(ver_info_bytes)
             version = f"{major}.{minor}.{patch}.{special} build {build}"
+            build_string = None
 
-            try:
-                build_string = await self.xncp_get_build_string()
-            except InvalidCommandError:
-                build_string = None
+            if FirmwareFeatures.BUILD_STRING in self._xncp_features:
+                with contextlib.suppress(InvalidCommandError):
+                    build_string = await self.xncp_get_build_string()
 
             if build_string:
                 version = f"{version} ({build_string})"

tests/test_ezsp.py

@@ -388,6 +388,9 @@ async def replacement(command_name, tokenId=None, valueId=None):
 
         return replacement
 
+    if not isinstance(xncp_build_string, InvalidCommandError):
+        ezsp_f._xncp_features |= xncp.FirmwareFeatures.BUILD_STRING
+
     with patch.object(
         ezsp_f,
         "_command",