can anybody explain the following to a git noob?

A transcript...

git init git add . > /dev/nul git commit -m 'initial import'

git status # On branch master nothing to commit (working directory clean)

***** Create new branch ******** git checkout -b my_branch Switched to a new branch "my_branch"

*********Try to rename a directory WTF?: Git thinks any directory with a .git folder is empty and refuses to rename the directory. git mv vendor vendor_new fatal: source directory is empty, source=vendor/plugins/acts_as_audited, destination=vendor_new/plugins/acts_as_audited

ls vendor/plugins/acts_as_audited/ CHANGELOG generators init.rb lib LICENSE Rakefile README spec tasks test.txt

******** Initial state of the test directory ls test fixtures functional integration mocks test_helper.rb unit watir

****** Rename and commit changes git mv test test_new git commit -m 'renamed the test directory'

********Current state of the directory
 ls
app  Capfile  config  db  doc  lib  MyProject.kpf  public  Rakefile  README
script  test_new  tmp  vendor

********Checkout master. WTF?: Both the test and the test_new directories exist. Why does the test_new exist in this branch? git checkout master ls app Capfile config db doc lib MyProject.kpf public Rakefile README script test test_new tmp vendor

******** list  the test directory.  WTF?: Where did the mocks subdir go??
(see above for the initial directory listing)
 ls test
fixtures  functional  integration  test_helper.rb  unit  watir

**** Check the test_new directory: WTF?: Where are all the other subdirectories? ls test_new functional mocks

******** Merge Everything is merged properly. git merge my_branch

ls app Capfile config db doc lib MyProject.kpf public Rakefile README script test_new tmp vendor ls test_new fixtures functional integration mocks test_helper.rb unit watir

obviously I am doing something profoundly wrong. Can somebody explain why this is happening?