test_capi.test_no_FatalError_infinite_loop crash on Windows

Python/pythonrun.c

 
 /* Python interpreter top-level routines, including init/exit */
 
 #include "Python.h"
 
 #include "Python-ast.h"
 #undef Yield /* undefine macro conflicting with winbase.h */
 #include "grammar.h"
 #include "node.h"
 #include "token.h"
@@ skipping 2068 matching lines @@
 
 void
 Py_FatalError(const char *msg)
 {
     fprintf(stderr, "Fatal Python error: %s\n", msg);
     fflush(stderr); /* it helps in Windows debug build */
     if (PyErr_Occurred()) {
         PyErr_PrintEx(0);
     }
 #ifdef MS_WINDOWS
-    {
+    if (IsDebuggerPresent()) {
         size_t len = strlen(msg);
         WCHAR* buffer;
         size_t i;
 
         /* Convert the message to wchar_t. This uses a simple one-to-one
         conversion, assuming that the this error message actually uses ASCII
         only. If this ceases to be true, we will have to convert. */
         buffer = alloca( (len+1) * (sizeof *buffer));
         for( i=0; i<=len; ++i)
             buffer[i] = msg[i];
         OutputDebugStringW(L"Fatal Python error: ");
         OutputDebugStringW(buffer);
         OutputDebugStringW(L"\n");
+#ifdef _DEBUG
+        DebugBreak();
+#endif
     }
-#ifdef _DEBUG
-    DebugBreak();
-#endif
 #endif /* MS_WINDOWS */
     abort();
 }
 
 /* Clean up and exit */
 
 #ifdef WITH_THREAD
 #include "pythread.h"
 #endif
 
@@ skipping 337 matching lines @@
 #undef PyRun_InteractiveLoop
 PyAPI_FUNC(int)
 PyRun_InteractiveLoop(FILE *f, const char *p)
 {
     return PyRun_InteractiveLoopFlags(f, p, NULL);
 }
 
 #ifdef __cplusplus
 }
 #endif