fix #663 in gpu mode

docker/hubserving/gpu/Dockerfile

@@ -8,7 +8,7 @@ RUN python3.7 -m pip install paddlepaddle-gpu==1.7.2.post107 -i https://pypi.tun
 
 RUN pip3.7 install paddlehub --upgrade -i https://pypi.tuna.tsinghua.edu.cn/simple
 
-RUN git clone https://gitee.com/PaddlePaddle/PaddleOCR
+RUN git clone https://gitee.com/PaddlePaddle/PaddleOCR /PaddleOCR
 
 WORKDIR /home/PaddleOCR
 
@@ -25,4 +25,4 @@ RUN tar xf /PaddleOCR/inference/ch_rec_mv3_crnn_infer.tar -C /PaddleOCR/inferenc
 
 EXPOSE 8866
 
-CMD ["/bin/bash","-c","export PYTHONPATH=. && hub install deploy/hubserving/ocr_system/ && hub serving start -m ocr_system"]
\ No newline at end of file
+CMD ["/bin/bash","-c","export PYTHONPATH=. && hub install deploy/hubserving/ocr_system/ && hub serving start -m ocr_system"]