Description of problem:

hdrFromFdno now fails on NOKEY, however it doesn't set the hdr so if you wanted
to have a policy in rpm python application of ignoring key checking you can't
inspect the error type.

Version-Release number of selected component (if applicable):

rpm-4.4.1-0.22


How reproducible:

Always

Steps to Reproduce:

rpm -E '%_hkp_keyserver'
%{unknown_macro}

generate key not imported to rpmdb/erase your signing key from rpmdb

rpm --resign simple-1.0-1.noarch.rpm
run test script

#!/usr/bin/python
import rpm,os,sys

ts = rpm.ts()
f = os.open("simple-1.0-1.noarch.rpm", os.O_RDONLY)

h = ts.hdrFromFdno(f)
os.close(f)
  
Actual results:

warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID 831ffbca
Traceback (most recent call last):
  File "testrpm.py", line 8, in ?
    h = ts.hdrFromFdno(f)
_rpm.error: public key not available


Expected results:

Works or definable policy with NOKEY handling

Additional info: