Analyse following RPM build log snippet. Describe contents accurately, without speculation or suggestions for resolution.            
Your analysis must be as concise as possible, while keeping relevant information intact.
Snippet: 
INFO: EXCEPTION: [Error()]
Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/mockbuild/trace_decorator.py", line 93, in trace
    result = func(*args, **kw)
  File "/usr/lib/python3.9/site-packages/mockbuild/util.py", line 600, in do_with_status
    raise exception.Error("Command failed: \n # %s\n%s" % (command, output), child.returncode)
mockbuild.exception.Error: Command failed: 
 # bash --login -c /usr/bin/rpmbuild -ba --noprep --target x86_64 --nodeps /builddir/build/SPECS/openstack-swift.spec

Error indicating failed mock build. It isn't actual cause of the issue, rather a stack trace of the build failure.