Despite that glaring flaw, the rest of hg is excellent. It functions almost identically to Subversion in the commands that it shares, and the new concepts - bra

Despite that glaring flaw, the rest of hg is excellent. It functions almost identically to Subversion in the commands that it shares, and the new concepts - branching, merging, etc. why exactly does the author refer to branching/merging as new concepts?