Hi,

Just updating this 6 year old bug report. The last comment says it's not possible to ignore environment when using the C-API. I don't know back then, but today it is possible. I have just built gdb 8.2 against python 3.7.1, and patched gdb with this simple patch, which apparently works:

--- gdb/python/python.c
+++ gdb/python/python.c
@@ -1726,6 +1726,9 @@
 #endif
 #endif

+  // Force using the toolchain python without being troubled by $PYTHONHOME or $PYTHONPATH.
+  Py_IgnoreEnvironmentFlag = 1;
+
   Py_Initialize ();
   PyEval_InitThreads ();

Cheers,
Romain