Paddle 启动报Fail to fscanf的warning，非常多

**Describe the bug (描述bug)**

19039 tests/llm/test_gradio.py::UITest::test_argument W0509 19:57:55.627235 81957 default_variables.cpp:95] Fail to fscanf: Success [0]
19040 W0509 19:57:55.659641 82036 default_variables.cpp:95] Fail to fscanf: Success [0]
19041 W0509 19:57:55.715762 82094 default_variables.cpp:95] Fail to fscanf: Success [0]
19042 W0509 19:57:55.776006 82226 default_variables.cpp:95] Fail to fscanf: Success [0]
19043 W0509 19:57:56.627295 81957 default_variables.cpp:95] Fail to fscanf: Success [0]
19044 W0509 19:57:56.659693 82036 default_variables.cpp:95] Fail to fscanf: Success [0]
19045 W0509 19:57:56.715819 82094 default_variables.cpp:95] Fail to fscanf: Success [0]
19046 W0509 19:57:56.776051 82226 default_variables.cpp:95] Fail to fscanf: Success [0]
19047 W0509 19:57:57.627346 81957 default_variables.cpp:95] Fail to fscanf: Success [0]
19048 W0509 19:57:57.659759 82036 default_variables.cpp:95] Fail to fscanf: Success [0]
**To Reproduce (复现方法)**

**Expected behavior (期望行为)**

**Versions (各种版本)**
OS:
Compiler:
brpc:
protobuf:

**Additional context/screenshots (更多上下文/截图)**

Start with the repeated warning at default_variables.cpp:95 and the reported tests/llm/test_gradio.py::UITest::test_argument output. Reproduce the startup or test scenario and inspect the fscanf failure path to determine why the warning is emitted repeatedly. Done means the underlying behavior is addressed and the warning no longer floods the output.

Written by the indexing model from the issue text.