Description of problem:
In 'mock' we change personality of system when we are building i686 package on x86_64 host. But bpersonality is set by 'rpm-python' only once when module is loaded. And can not be changed later. So we must workaround it by lazy import of rpm module.

It would be nice if you can provide some function, which would re-read personality and re-inicialize it.


How reproducible:
Create evil.spec with:
BuildArch i686

And try:
#!/usr/bin/python
import ctypes
# taken from sys/personality.h
PER_LINUX32=0x0008
PER_LINUX=0x0000
personality_defs = {
    'x86_64': PER_LINUX, 'ppc64': PER_LINUX, 'sparc64': PER_LINUX,
    'i386': PER_LINUX32, 'i586': PER_LINUX32, 'i686': PER_LINUX32,
    'ppc': PER_LINUX32, 'sparc': PER_LINUX32, 'sparcv9': PER_LINUX32,
    'ia64' : PER_LINUX, 'alpha' : PER_LINUX,
    's390' : PER_LINUX32, 's390x' : PER_LINUX,
}
_libc = ctypes.cdll.LoadLibrary(None)

#SWAP
_libc.personality(personality_defs['i686'])
import rpm

ts = rpm.ts()
ts.parseSpec('evil.spec')


This will work.
But if you swap those two lines after #SWAP, then if will not work and fail with:

error: No compatible architectures found for build
Traceback (most recent call last):
  File "/tmp/test", line 22, in <module>
    ts.parseSpec('evil.spec') 
  File "/usr/lib64/python2.7/site-packages/rpm/transaction.py", line 41, in parseSpec
    return _rpmb.spec(specfile)
ValueError: can't parse specfile