[Monotone-devel] How do I merge 2 unrelated branches into 1 ?

[Dmitry Kakurin]

I have two unrelated branches called HSM and Main. Now I want to
combine them into one.
But this is what I'm getting:

U:\Work>mtn propagate HSM Main
mtn: propagating HSM -> Main
mtn: [source] 94253d793cff0104c03589793756f7420df11aa4
mtn: [target] ad0b531e0093c2aa4f02e70b908e550784962082
mtn: warning: rename target conflict: nodes 55, 1, both want parent 0, name
mtn: warning: resolve non-content conflicts and then try again.
mtn: error: merge failed due to unresolved conflicts

What does it mean and how do I fix it ?