Handle new descriptions of detached head introduced in git 1.8.3

By @ch3cooli on June 06, 2013 14:08 (imported from Google Code)

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What steps will reproduce the problem?

1. TortoiseGit -> Switch / Checkout
2. Choose a commit (hash), not branch or tag
3. Click OK, the repository goes to detached head state
4. TortoiseGit -> Switch / Checkout

What is the expected output? What do you see instead?
Expected: branch combo box defaults to empty
Actual: branch combo box shows "(detached from faceb00)"

What version of TortoiseGit and msysgit are you using? On
what operating system?
TortoiseGit 1.8.3
msysgit 1.8.3
Win 7 x64