frustrated forensics: hard to find diff that undid a fix

I made a fix a month ago on the master branch in a shared repo. A week later, a colleague did a merge that undid the fix. I didn't figure out the problem until just now because I'd been assuming the fix was still on master. I mean, if it wasn't, I should see a reverse patch using "git log -p master", right? Wrong. Turns out the fix was undone as part of merge conflict resolution (I think).

Is there some way to include merge conflict resolutions in "git log -p" or "git show"? Apparently some important information can be hidden in the conflict resolution. Or, more likely, I just don't understand how this bit of git works.

I also tried bisect and pickaxe. Bisect wrongly identified the first bad commit, and pickaxe just didn't see the change at all.

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Here's some details in case anyone wants to (a) point out where I messed up or (b) help me avoid this kind of blunder in the future.

1. The repo is git://mifos.git.sourceforge.net/gitroot/mifos/head
(mirror: https://github.com/mifos/head ). Branch master.

2. My commit 2a1ed0436 introduced a fix that includes the text
"native2ascii". Shows up in "git log -p -1 2a1ed0436" and "git show
2a1ed0436". Life is good.

3. It appears that the merge commit 0f8132386 tossed my "native2ascii"
fix. The only way I could figure out to actually visualize this is "git
diff 58320586..0f813238".

This took a while to figure out. Am I missing something obvious?