Finding the date/time a file appeared in a git branch

Question

How is possible to get the date in which a file appeared for the first time in a branch.

Currently I'm using the following. The problem is that for merges it returns the creation date in the original branch instead of returning the date of the merge.

$ git log --first-parent --format=%ct FILE

Answer 1

Looks like this problem is fixed in version 1.7.9.1 https://github.com/git/git/blob/master/Documentation/RelNotes/1.7.9.1.txt