Merge pull request #5110 from jtattermusch/fix_python_jessie_x86

Make python jessie x86 distribtest pass

tools/dockerfile/distribtest/python_jessie_x86/Dockerfile

@@ -30,3 +30,8 @@
 FROM 32bit/debian:jessie
 
 RUN apt-get update && apt-get install -y python python-pip
+
+# docker is running on a 64-bit machine, so we need to
+# override "uname -m" to report i686 instead of x86_64, otherwise
+# python will choose a wrong binary package to install.
+ENTRYPOINT ["linux32"]