build_container: Avoid pip install with &&

Even if we have `set -e`, if `pip install` fails, the script goes on
because we use the && operator.

Avoid this to make sure that we discover any errors with `pip install`.

Signed-off-by: Ruoqing He <heruoqing@iscas.ac.cn>

Author: RuoqingHe

build_container.sh

@@ -51,7 +51,8 @@ fi
 
 # Allow pip to install packages system wide
 rm /usr/lib/python3.*/EXTERNALLY-MANAGED
-pip3 install --no-cache-dir pytest pexpect boto3 pytest-timeout && apt purge -y python3-pip
+pip3 install --no-cache-dir pytest pexpect boto3 pytest-timeout
+apt purge -y python3-pip
 
 # Install rustup and a fixed version of Rust.
 curl https://sh.rustup.rs -sSf | sh -s -- \