Roman Catholic Teaching: "Cheating in an examination at school is not sinful unless it brings injustice to others"?

Every so often I come across something that simply seems too ridiculous to be true, like a few weeks ago when the Vatican was said to be offering indulgences to the Pope's Twitter followers (that one turned out to be true). A few days ago, I came across the following on an Internet discussion board, and this one also seemed far-fetched:

"Cheating in an examination at school is not sinful unless it brings injustice to others." From the New Parish Catechism  Imprimatur: Most Rev. Joseph A. Durick, DD Bishop of Nashville.

I inquired about the quote, and this was the answer I was given:

Sorry to say this is not a misquote but the actual quote taken from the new parish catechism. I'll give you also the Nihil Obstat: Rev. Robert J. Hofstetter. Imprimatur: Most Rev. Joseph A. Durick D. D. Bishop of Nashville. Copyright 1973 by Fare Revised 1976. Now as a "Born Again" believer I take lying as a mortal sin because the Word of God declares that no liar will enter into the Kingdom of Heaven. I am not saying anyone here is calling me a liar but I just want to set the record straight. I don,t know what else to say except I am accountable to the Lord for not presenting the truth. It is what it is.

I Googled the quote and book, but couldn't find any copies available online, so I bought one. Sure enough, the quote is there (p.131). The quote is part of "Lesson 42: The Eighth Commandment" (You shall not bear false witness against your neighbor). The lesson goes along rather smoothly until section 5 which explains, "Sins against the Eighth Commandment are serious if damage results from your misuse of the power of speech. If the damage done is less serious the sin is venial." Then in section 6, the quote in question occurs:

6. What is a lie?
A lie is a violation of my neighbor's right to truth. A lie is a distortion of truth.
"Lying is an abominable habit." (Sirach 20:26)
Hyperbole (exaggeration) and telling an untruth as a joke are not necessarily sinful.
Cheating in an examination at school is not sinful unless it brings injustice to others.
Perjury (lying under oath) is the most serious way to violate speech and human trust. Perjury is, therefore, a most serious sin. Teachers and parents are the agents of truth. Television, radio, the press are also agents of truth and are obliged to tell the truth without fiction or exaggeration.

Documentation:
Rev. William G. Martin, The New Parish Catechism, A Complete Course in the Catholic Faith, the Teachings of Jesus Christ (Ill.:FARE INC., 1973), p.131.

"Useful and practical for many uses in the parish"

Nihil Obstat: Rev. Robert J. Hofstetter Censor Librorum

Imprimatur: Most Rev. Joseph A. Durick, D.D. Bishop of Nashville

The Nihil Obstat and Imprimatur are official declarations that a book or pamphlet is free of doctrinal or moral error.  No implication is contained therein that those who have granted the Nihil Obstat and Imprimatur agree with the contents, opinions or statements expressed.

Addendum
I've been told that the revised edition of this catechism (1986) is changed at this section. If anyone has a copy of it, please post the changes here.