Fix print of git-remote-persistent-https error

If git-remote-persistent-https fails, we use an iter() and then
subsequently a .read() on stderr.  Python doesn't like this and
gives the following error message:
ValueError: Mixing iteration and read methods would lose data

This change removes the use of iter() to avoid the issue.

Change-Id: I980659b83229e2a559c20dcc7b116f8d2476abd5
1 file changed