Caffe: GPU 0 is also used when running on other GPUs (#440 reocurred?)

I just built caffe-rc2 with CUDA 7.0 and Driver 346.47. When running the test on my first GPU (with id 0), everything works fine. However, when running the test on 2nd GPU (with id 1, or build/test/test_all.testbin 1), the command nvidia-smi shows that both GPUs are being used. This is not the case when I'm running the test on GPU0, nor when I'm running the test using caffe-rc1 (built with CUDA 6.5 a while ago). I tried building caffe-rc2 using CUDA 6.5, and the problem persists.

By setting export CUDA_VISIBLE_DEVICES=1, and running build/test/test_all.testbin 0, the problem disappeared. So this seems like a problem like that in https://github.com/BVLC/caffe/issues/440?

Update: when I ran build/test/test_all.testbin 1 --gtest_filter=DataLayerTest*, with my GPU0's memory filled up using some other software (cuda_memtest in my case), the program failed:

build/test/test_all.testbin 1 --gtest_filter=DataLayerTest/3*
Cuda number of devices: 2
Setting to use device 1
Current device id: 1
Note: Google Test filter = DataLayerTest/3*
[==========] Running 12 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 12 tests from DataLayerTest/3, where TypeParam = caffe::DoubleGPU
[ RUN      ] DataLayerTest/3.TestReadLevelDB
F0324 20:34:20.499236 20499 benchmark.cpp:111] Check failed: error == cudaSuccess (2 vs. 0)  out of memory
*** Check failure stack trace: ***
    @     0x7f16777cfdaa  (unknown)
    @     0x7f16777cfce4  (unknown)
    @     0x7f16777cf6e6  (unknown)
    @     0x7f16777d2687  (unknown)
    @     0x7f1675f133b8  caffe::Timer::Init()
    @     0x7f1675f13569  caffe::CPUTimer::CPUTimer()
    @     0x7f1675ebacec  caffe::DataLayer<>::InternalThreadEntry()
    @     0x7f166de8da4a  (unknown)
    @     0x7f16755f5182  start_thread
    @     0x7f167532247d  (unknown)
    @              (nil)  (unknown)
Aborted (core dumped)

With other test categories (at least NeuronLayerTest and FlattenLayerTest), the program works fine.