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!