disable the CUDA back-end if nvcc is not there even if we can load cuda_ndarray.so

theano/sandbox/cuda/__init__.py

@@ -163,6 +163,13 @@ if compile_cuda_ndarray:
                 set_cuda_disabled()
     finally:
         release_lock()
+elif not nvcc_compiler.is_nvcc_available():
+    # This can happen if there is cuda_ndarray.so was already compiled
+    # and then nvcc is removed. In that case we need to disable the CUDA
+    # back-end as we won't be able to compile any new op and we can't only
+    # use already compiled GPU op and not the others.
+    set_cuda_disabled()
+
 del compile_cuda_ndarray
 
 if cuda_available: