Description of problem:
Both testHostSampleHandlesDisappearingVlanInterfaces and testHostSampleReportsNewInterface are failing due to IOError: No such file or directory: '/etc/pki/vdsm/keys/libvirt_password'. Both the testcases are lookng for libvirt_password file which will be installed with package installation. It is not appropriate for a testcase to look for a file which will be installed after the package is installed.


Version-Release number of selected component (if applicable):
master branch (077ae1d04e1af695c9ec8b76ed9d0c32468230db)


How reproducible:
Always


Steps to Reproduce:
1. git clone git://gerrit.ovirt.org/vdsm
2. cd ./vdsm
3. ./autogen.sh
4. make 
5. make check

Actual results:
======================================================================
ERROR: testHostSampleHandlesDisappearingVlanInterfaces (samplingTests.InterfaceSampleTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/tests/testValidation.py", line 105, in wrapper
    return f(*args, **kwargs)
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/tests/samplingTests.py", line 172, in testHostSampleHandlesDisappearingVlanInterfaces
    hs = sampling.HostSample(os.getpid())
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/vdsm/virt/sampling.py", line 281, in init
    self.numaNodeMem = NumaNodeMemorySample()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/vdsm/virt/sampling.py", line 167, in init
    numaTopology = caps.getNumaTopology()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/vdsm/caps.py", line 326, in getNumaTopology
    capabilities = _getCapsXMLStr()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/vdsm/caps.py", line 227, in _getCapsXMLStr
    return _getFreshCapsXMLStr()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/vdsm/caps.py", line 222, in _getFreshCapsXMLStr
    return libvirtconnection.get().getCapabilities()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/lib/vdsm/libvirtconnection.py", line 163, in get
    passwd = _read_password()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/lib/vdsm/libvirtconnection.py", line 81, in _read_password
    with open(constants.P_VDSM_LIBVIRT_PASSWD) as passwd_file:
IOError: [Errno 2] No such file or directory: '/etc/pki/vdsm/keys/libvirt_password'
-------------------- >> begin captured logging << --------------------
root: DEBUG: /sbin/ip link add name dummy_7OXt0 type dummy (cwd None)
root: DEBUG: SUCCESS: <err> = ''; <rc> = 0
root: DEBUG: /sbin/ip link add link dummy_7OXt0 name vlan_245 type vlan id 999 (cwd None)
root: DEBUG: SUCCESS: <err> = ''; <rc> = 0
root: DEBUG: /sbin/ip link del dev vlan_245 (cwd None)
root: DEBUG: SUCCESS: <err> = ''; <rc> = 0
root: DEBUG: trying to connect libvirt
root: DEBUG: /sbin/ip link del dev vlan_245 (cwd None)
root: DEBUG: FAILED: <err> = 'Cannot find device "vlan_245"\n'; <rc> = 1
root: DEBUG: /sbin/ip link del dev dummy_7OXt0 (cwd None)
root: DEBUG: SUCCESS: <err> = ''; <rc> = 0
--------------------- >> end captured logging << ---------------------

======================================================================
ERROR: testHostSampleReportsNewInterface (samplingTests.InterfaceSampleTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/tests/testValidation.py", line 105, in wrapper
    return f(*args, **kwargs)
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/tests/samplingTests.py", line 150, in testHostSampleReportsNewInterface
    hs_before = sampling.HostSample(os.getpid())
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/vdsm/virt/sampling.py", line 281, in init
    self.numaNodeMem = NumaNodeMemorySample()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/vdsm/virt/sampling.py", line 167, in init
    numaTopology = caps.getNumaTopology()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/vdsm/caps.py", line 326, in getNumaTopology
    capabilities = _getCapsXMLStr()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/vdsm/caps.py", line 227, in _getCapsXMLStr
    return _getFreshCapsXMLStr()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/vdsm/caps.py", line 222, in _getFreshCapsXMLStr
    return libvirtconnection.get().getCapabilities()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/lib/vdsm/libvirtconnection.py", line 163, in get
    passwd = _read_password()
  File "/root/rpmbuild/BUILD/vdsm-4.17.0/lib/vdsm/libvirtconnection.py", line 81, in _read_password
    with open(constants.P_VDSM_LIBVIRT_PASSWD) as passwd_file:
IOError: [Errno 2] No such file or directory: '/etc/pki/vdsm/keys/libvirt_password'
-------------------- >> begin captured logging << --------------------
root: DEBUG: trying to connect libvirt
--------------------- >> end captured logging << ---------------------

----------------------------------------------------------------------
Ran 887 tests in 102.209s

FAILED (SKIP=31, errors=2)

Expected results:
Complete make check will no errors


Additional info:
These failures can be fixed bi letting the testcases to look for the libvirt_password file in sources if the file is not present in '/etc/pki/vdsm/keys/libvirt_password' location.