The Jargon File (version 4.4.7, 29 Dec 2003):
one-line fix
 n.
    Used (often sarcastically) of a change to a program that is thought to be
    trivial or insignificant right up to the moment it crashes the system.
    Usually ?cured? by another one-line fix. See also I didn't change
    anything!
The Free On-line Dictionary of Computing (30 December 2018):
one-line fix
   Used (often sarcastically) of a change to a program that is
   thought to be trivial or insignificant right up to the moment
   it crashes the system.  Usually "cured" by another one-line
   fix.  See also I didn't change anything!