An Act of Contrition is a Steven Brust story in the first Liavek book, Liavek, City of Luck and Wizardry.
The Megan Lindholm story in Liavek, Wizard's Row often listed as "An Act of Contrition" is actually titled An Act of Mercy. This is the case even on Megan's own website.
"An Act of Mercy" was co-written with Brust which is probably the reason for the confusion.
books: City of Luck and Wizardry | Players of Luck | Wizard's Row | Spells of Binding
stories: A Coincidence of Birth | Pot Luck | An Act Of Mercy | An Act of Love