I am looking for the mercurial equivalent of the solution to this question:
How do I "git blame" a deleted line?
In short, I am looking at a mercurial commit where a line was added, and in the current revision this line is no longer present, and I want to find when and why it was removed.
hg histgrep will let you search a change log for a pattern, such as a deleted string. If you are looking for more than just the first occurrence, be sure to include the --all flag. For me it looked something like this:
hg histgrep --all -r 9876:tip "pattern" path/to/file
Thanks to Anton for the helpful comments and krtek for his related answer.