I think what @drbrains might have been hinting at is that one or both of those commits may have "broken" the build.
@slh suggesting using
git bisect to locate the "first bad" commit is a good one, pone I have used myself several times. The manual for
git bisect is pretty good, but basically you "start" with a known-bad commit, checkout another commit (that you already know is good), build it, test it, confirm that it's good, then mark it as "good" with git. The git system will then start checking out commits for you to test, being "smart" about it, so that you generally only have to check ~log2(number from bad to good) commits. You can find the "first bad" commit over 100 commits in about 7 tests or so.
There's a "worked example" of using
git bisect at https://git-scm.com/book/en/v2/Git-Tools-Debugging-with-Git