overwrite symbol link 

lrwxrwxrwx. 1 root root 20 Oct 17 13:17 /etc/mock/default.cfg ->
fedora-21-x86_64.cfg
lrwxrwxrwx. 1 root root 25 Nov 17 22:23 /etc/mock/default.cfg.rpmnew ->
fedora-rawhide-x86_64.cfg

Traceback (most recent call last):
  File "/sbin/rpmconf", line 318, in <module>
    main()
  File "/sbin/rpmconf", line 311, in main
    handle_package(args, package_hdr)
  File "/sbin/rpmconf", line 217, in handle_package
    handle_rpmnew(args, conf_file, conf_file + ".rpmnew")
  File "/sbin/rpmconf", line 159, in handle_rpmnew
    overwrite(args, other_file, conf_file)
  File "/sbin/rpmconf", line 43, in overwrite
    copy(src, dst)
  File "/sbin/rpmconf", line 35, in copy
    os.symlink(linkto, dst)
FileExistsError: [Errno 17] File exists: 'fedora-rawhide-x86_64.cfg' ->
'/etc/mock/default.cfg'

Reference: https://github.com/xsuchy/rpmconf/issues/11
Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>
Merge pull request #15 from ignatenkobrain/symlink

overwrite symbol link
remove unused imports
remove trailing whitespace
disable some pylint warnings
C: 68, 0: Unnecessary parens after not keyword (superfluous-parens)
C:321, 0: No space allowed after bracket
        packages = [ ts.dbMatch() ]
                   ^ (bad-whitespace)
C:321, 0: No space allowed before bracket
        packages = [ ts.dbMatch() ]
                                  ^ (bad-whitespace)
waive E:321,24: Instance of TransactionSet has no dbMatch member (no-member)
skip /var/lib/mock when --clean

otherwise we would be checking buildroots of mock
move pylint directives up
R:254, 0: Too many branches (15/12) (too-many-branches)
make pylint run mandatory
no dot generate reports