As noted in a prior answer, although git merge-base works,
$ git merge-base myfeature develop
050dc022f3a65bdc78d97e2b1ac9b595a924c3f2
If myfeature is the current branch, as is common, you can use --fork-point:
$ git merge-base --fork-point develop
050dc022f3a65bdc78d97e2b1ac9b595a924c3f2
This argument works only in sufficiently recent versions of git. Unfortunately it doesn't always work, however, and it is not clear why. Please refer to the limitations noted toward the end of this answer.
For full commit info, consider:
$ git log -1 $(git merge-base --fork-point develop)