The Jargon File (version 4.4.7, 29 Dec 2003):

banana problem
 n.

    [from the story of the little girl who said ?I know how to spell ?banana?,
    but I don't know when to stop?]. Not knowing where or when to bring a
    production to a close (compare fencepost error). One may say there is a
    banana problem of an algorithm with poorly defined or incorrect termination
    conditions, or in discussing the evolution of a design that may be
    succumbing to featuritis (see also creeping elegance, creeping
    featuritis). See item 176 under HAKMEM, which describes a banana problem
    in a Dissociated Press implementation. Also, see one-banana problem for
    a superficially similar but unrelated usage.


The Free On-line Dictionary of Computing (30 December 2018):

banana problem
banana phenomenon

    From the story of the little girl who
   said "I know how to spell "banana", but I don't know when to
   stop".  Not knowing where or when to bring a production to a
   close (compare fencepost error).  One may say "there is a
   banana problem" of an algorithm with poorly defined or
   incorrect termination conditions, or in discussing the
   evolution of a design that may be succumbing to featuritis
   (see also creeping elegance, creeping featuritis).

   HAKMEM item 176 describes a banana problem in a Dissociated
   Press implementation.  Also, see one-banana problem for a
   superficially similar but unrelated usage.

   (2010-03-20)