I assume the default
tag you see isn't about the revision but the branch you're working on. That being said, check your current active heads by typing this:
hg heads
If you've got multiple heads, that means that you haven't merged everything back to the core line of the actual branch.
If it is the case, commit all your work (which will fall automatically into a new temporary branch). Then, pull the last revision from the source and then merge :
hg pull && hg merge
If there is a problem while on the pull/merging stage, try updating your current repository to a clean one by issuing this command:
hg update -C # Only if you've got problems with the previous command!
And then retry the merge operation.
I may have misunderstood your problem since I couldn't grasp all of your environment status, if it is the case, please excuse me.