[SSSD] [sssd PR#486][comment] TOOLS: Fix typo: exist -> exists

[lslebodn]

  URL: https://github.com/SSSD/sssd/pull/486
Title: #486: TOOLS: Fix typo: exist -> exists

lslebodn commented:
"""
master:
* 9be0fce9bc1f48241425726ddd612ffd64556715
"""

See the full comment at https://github.com/SSSD/sssd/pull/486#issuecomment-354973157