Handle fast-forward merges properly in repository.performRebase#1457

Merged

implausible merged 3 commits intonodegit:masterfrom

cjhoward92:fix/rebase-ff-merge

Mar 16, 2018

Commits on Mar 12, 2018

Handle fast-forward merges in repository.performRebase
Carson Howard
committed

Commits on Mar 13, 2018

Added a unit test and better comments
Carson Howard
committed

Commits on Mar 15, 2018

Replace fse.existsSync with a catch on fse.readFile
Carson Howard
committed