Martin, I applied your patch and it proved your hypothesis. See below for how I tested. I also updated the github repo for others to reproduce if they wish.


cd
wget https://www.python.org/ftp/python/3.5.0/Python-3.5.0.tar.xz

mkdir ~/dist
cd ~/dist
tar xJf ~/Python-3.5.0.tar.xz
cd Python-3.5.0
./configure --prefix=/home/vagrant/py35/dist && \
make && make install

mkdir ~/patch
cd ~/patch
tar xJf ~/Python-3.5.0.tar.xz
cd Python-3.5.0
patch -p1 < /vagrant/fstat-failure.patch
./configure --prefix=/home/vagrant/py35/patch && \
make && make install



vagrant@vagrant-ubuntu-trusty-64:~$ ./py35/dist/bin/python3.5 /vagrant/temptest.py 
Path 1: worked
Path 2: ERROR
vagrant@vagrant-ubuntu-trusty-64:~$ ./py35/patch/bin/python3.5 /vagrant/temptest.py 
Path 1: worked
Path 2: worked