Possible solution (not tested)

GetFromTo.cs

public virtual IEnumerable<Commit> GetFromTo(DateTime start, DateTime end)
{
	this.ThrowWhenDisposed();
	Logger.Debug(Resources.GettingAllCommitsFromToTime, start, end);

	var selectedCommitIds = this.stamps.Where(x => x.Value >= start && x.Value < end).Select(x => x.Key);
	var firstCommitId = selectedCommitIds.FirstOrDefault();
	var lastCommitId = selectedCommitIds.LastOrDefault();

	if (lastCommitId == Guid.Empty && lastCommitId == Guid.Empty)
		return new Commit[] { };

	var startingCommit = this.commits.FirstOrDefault(x => x.CommitId == firstCommitId);
	var endingCommit = this.commits.FirstOrDefault(x => x.CommitId == lastCommitId);

	var startingCommitIndex = (startingCommit == null) ? 0 : this.commits.IndexOf(startingCommit);
	var endingCommitIndex = (endingCommit == null) ? this.commits.Count - 1 : this.commits.IndexOf(endingCommit);
	var numberToTake = endingCommitIndex - startingCommitIndex + 1;

	return this.commits.Skip(this.commits.IndexOf(startingCommit)).Take(numberToTake);
}