How do I undo 'git add' before commit?

Answer 1

Note that if you fail to specify a revision then you have to include a separator. Example from my console:

git reset 
fatal: ambiguous argument '': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions

git reset -- 
Unstaged changes after reset:
M    

(Git version 1.7.5.4)