git

現在地がわからなくなっているらしい

git status
=> index small

rm .git/index

git status
#
# Initial commit
#

git log
=> fatal: bad default revision 'HEAD'

cd .git

vi logs/refs/heads/<branch name>
  0000000000000000000000000000000000000000 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx sakahukamaki <mail> 1497499755 +0900  branch: Created from HEAD
  xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu sakahukamaki <mail> 1497499768 +0900  commit: README.mdに追記
  uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu dddddddddddddddddddddddddddddddddddddddd sakahukamaki <mail> 1497509827 +0900  commit: save

git show dddddddddddddddddddddddddddddddddddddddd 
=> それっぽいコミット

vi HEAD
=>  ref: refs/heads/<branch name>

vi refs/heads/<branch name>
=> 空

"dddddddddddddddddddddddddddddddddddddddd "を追記

解決