Hello,

we observe a failure in RPM job executed as part of Component CI for OSP 18

```
ironic.tests.unit.drivers.modules.test_pxe.PXEBootTestCase.test_prepare_instance_kickstart_bios
-----------------------------------------------------------------------------------------------

Captured traceback:
~~~~~~~~~~~~~~~~~~~
Traceback (most recent call last):

File "/usr/lib64/python3.9/unittest/mock.py", line 1336, in patched
return func(*newargs, **newkeywargs)

File "/home/zuul/src/code.engineering.redhat.com/ironic/ironic/tests/unit/drivers/modules/test_pxe.py", line 653, in test_prepare_instance_kickstart_bios
task.driver.boot.prepare_instance(task)

File "/usr/lib/python3.9/site-packages/ironic_lib/metrics.py", line 60, in wrapped
result = f(*args, **kwargs)

File "/home/zuul/src/code.engineering.redhat.com/ironic/ironic/drivers/modules/pxe_base.py", line 249, in prepare_instance
pxe_utils.validate_kickstart_file(ks_cfg)

File "/home/zuul/src/code.engineering.redhat.com/ironic/ironic/common/pxe_utils.py", line 1164, in validate_kickstart_file
ks_file.write(ks_cfg)

File "/usr/lib64/python3.9/tempfile.py", line 478, in func_wrapper
return func(*args, **kwargs)

TypeError: write() argument must be str, not MagicMock
```

What we do in the job, is:
– we fetch the spec file and install the RPM dependencies listed there,
– we install some missing RPMs identified (that should be in spec file probably, but they are not),
– we run the tests defined in tox.

The additional RPMs we install are listed here:
https://github.com/RedHatCRE/znoyder/blob/6e728306f860ed90054144fefa454d5cd90cc4d0/znoyder/config.d/43-override-OSP-18.yml#L103

So, in essence, this is a tox job but with truncated requirement.txt and site-packages enabled.

You can use this change for debugging the issue.
https://code.engineering.redhat.com/gerrit/c/ironic/+/445376

Yours,
Szymon