I was using gvim as editor.
Inspite of using proper commit message and quitting gvim properly ( top question in stackoverflow :)),
it failed with message "Aborting commit due to empty commit message."
$ git commit
Aborting commit due to empty commit message.
All you need to do is :
git config core.editor "gvim -f"
Then, try git commit , it should work.
Why it failed ?
Looking at man gvim:
-f Foreground. This option should be used when Vim is executed by a program that
will wait for the edit session to finish (e.g. mail).