commit: get info from mergestate whether a file was merged or not While commiting a merge, the commit code does not know whether a file was merged during `hg merge` or not. This leads the commit code to look for filelog ancestor to choose parents of new filelog created on merge commit. This leads to wrong results in some cases as demonstrated by previous patch. From this patch, we start storing information about merged files in mergestate in stateextras and then use that on commit to detect whether we need to set two parents or not. Differential Revision: https://phab.mercurial-scm.org/D10149