Git question - finding a commit in the history

[colin.helliwell at ln-systems.com]

I've been building for a few months on a particular git commit
(3e15dc15efd118a2e7af8f60727afc7fbb7db3a3). I'm planning to try out the
latest Master - hopefully in readiness of a tagged release occurring soon.
In case I encounter 'brokenness' on my system, and need to track through
logs, is there an easy way to find this commit? (I should have added a
comment into my config file at the time....!)
Thanks