Patch Set 3:

I started another try from a new fresh workspace:

- start test IDE containing your change
- clone egit from git://egit.eclipse.org/egit.git
- create a tag test-1 on egit
- select project org.eclipse.egit in package explorer
- Team > Show in Resource History

-> NumberFormatException in error log, this time the input string is  "2235249 +0200"