remove a file from the most recent git commit with 'git reset'

How to quickly and easily remove a file from your most recent git commit while maintaing the changes in the working directory. Use 'git reset HEAD^' followed by 'git commit --amend'.

Caveats: Don't modify your commits if they've been pushed upstream or shared (unless you know why and how and ... no, just don't).

git reset HEAD^ -- $file
git commit --amend

Notes:

1. This technique works nicely if you need to modify a previous commit by wrapping it inside a 'git rebase -i ...' and then 'edit'ing the commit you want.
2. My right-hand prompt shows the VCS system (git), branch and git status. zsh's vcs_info is AWESOME.
3. Yes, I do have a smiley face in my prompt. It goes from a green happy face to a red sad face if the last command failed.

Short Example:

% git add a b c
% git commit -m "adds a and c"
# realize I didn't mean to include b!
% git reset HEAD^ -- b
% git commit --amend

Full Example:

[vm53@vm53]% git status                                 :) (git)-[master] ~/src/bar
# On branch master
nothing to commit (working directory clean)
[vm53@vm53]% echo "a" > a; echo "b">b; echo "c">c       :) (git)-[master] ~/src/bar
[vm53@vm53]% git status                                 :) (git)-[master] ~/src/bar
# On branch master
# Untracked files:
#   (use "git add ..." to include in what will be committed)
#
#       a
#       b
#       c
nothing added to commit but untracked files present (use "git add" to track)
[vm53@vm53]% git add a b c                              :) (git)-[master] ~/src/bar
[vm53@vm53]% git commit                                 :) (git)-[master] ~/src/bar
### editor opens with the old git message, modify if desired
[master 18d73bd] adds a and c
 3 files changed, 3 insertions(+), 0 deletions(-)
 create mode 100644 a
 create mode 100644 b
 create mode 100644 c
[vm53@vm53]% git status                                 :) (git)-[master] ~/src/bar
# On branch master  
nothing to commit (working directory clean)
[vm53@vm53]% git reset HEAD^ -- b                       :) (git)-[master] ~/src/bar
[vm53@vm53]% git status                                 :) (git)-[master] ~/src/bar
# On branch master
# Changes to be committed:
#   (use "git reset HEAD ..." to unstage)
#
#       deleted:    b
#
# Untracked files:
#   (use "git add ..." to include in what will be committed)
#
#       b
[vm53@vm53]% git commit --amend -m "adds a and c"       :) (git)-[master] ~/src/bar
[master c15220b] adds a and c
 2 files changed, 2 insertions(+), 0 deletions(-)
 create mode 100644 a
 create mode 100644 c
[vm53@vm53]% git status                                 :) (git)-[master] ~/src/bar
# On branch master
# Untracked files:
#   (use "git add ..." to include in what will be committed)
#
#       b
nothing added to commit but untracked files present (use "git add" to track)
[vm53@vm53]%                                            :) (git)-[master] ~/src/bar