I'm new to collaborating with Mercurial. My situation:

• Another programmer changed rev 1 of a file to replace 4-space indents with 2-space indent. (I.e. changed every line.) Call that rev 2, pushed to the remote repo.
• I've committed substantive changes rev 1 with various code changes in my local workspace. Call that rev 3.
• I've hg pulled and hg mergeed without a clear idea of what was going on.
• The conflicts are myriad and not really substantive.

So I really wish I'd changed my local repo to 2-space indents before merging; then the merge will be trivial (i'm supposing). But I can't seem to back up. I think I need to hg update -r 3 but it says abort: outstanding uncommitted merges.

How can I undo the merge, changes spacing in my local repo, and remerge?