qa/tasks/qemu: open file in text mode

in python3, if a file is opened in 'rb' mode, we will have bytes when
reading from it, as a result, we have following failure like:
```
Traceback (most recent call last):
  File "/home/teuthworker/src/git.ceph.com_git_teuthology_master/teuthology/contextutil.py", line 32, in nested
    vars.append(enter())
  File "/usr/lib/python3.6/contextlib.py", line 81, in __enter__
    return next(self.gen)
  File "/home/teuthworker/src/github.com_tchaikov_ceph_nautilus-py3/qa/tasks/qemu.py", line 124, in generate_iso
    test_setup = ''.join(f.readlines())
TypeError: sequence item 0: expected str instance, bytes found
```

Signed-off-by: Kefu Chai <kchai@redhat.com>
(cherry picked from commit 0b21c597d438fcba43629d0795b2d4ff6112c9cf)

diff --git a/qa/tasks/qemu.py b/qa/tasks/qemu.py
index 0b77ff5d310f1d4b6fc06ca24bd00cf956362576..d85eff38945dcd460c594fcd252367987ff88bd2 100644 (file)
--- a/qa/tasks/qemu.py
+++ b/qa/tasks/qemu.py
@@ -122,7 +122,7 @@ def generate_iso(ctx, config):
         userdata_path = os.path.join(testdir, 'qemu', 'userdata.' + client)
         metadata_path = os.path.join(testdir, 'qemu', 'metadata.' + client)
 
-        with open(os.path.join(src_dir, 'userdata_setup.yaml'), 'rb') as f:
+        with open(os.path.join(src_dir, 'userdata_setup.yaml')) as f:
             test_setup = ''.join(f.readlines())
             # configuring the commands to setup the nfs mount
             mnt_dir = "/export/{client}".format(client=client)
@@ -130,7 +130,7 @@ def generate_iso(ctx, config):
                 mnt_dir=mnt_dir
             )
 
-        with open(os.path.join(src_dir, 'userdata_teardown.yaml'), 'rb') as f:
+        with open(os.path.join(src_dir, 'userdata_teardown.yaml')) as f:
             test_teardown = ''.join(f.readlines())
 
         user_data = test_setup