It seems there is a bug in the current RubyStack for Windows (ruby 18.6 release).
It appears when the RubyStack DOS Windows has width of more than 80 characters.
The simplest way to reproduce it:
I. Setup the window width:
1. Open BitNami DOS Window
2. Click on upper-left small icon on the Window
4. Set “Screen Buffer Size” Width and “Windows Size” Width to 100->OK->
5. You may want not to change the permanent properties settings; so just click OK in the appeared new window to close the Properties dialog
The Window gets wider.
II. Start console:
6. In the DOS Window: cd to your project
7. ruby script/console
The prompt appears:
III. Reproduce the error:
8. Enter any string of more than 80 characters into the command line. Eg. enter “xxxxx…..xxxx”.
9. Hit the back-arrow key several times until the cursor moves to the position of less-then-80
10. See what happen.
Using wide window is very convenient for entering/editing longer command strings. The bug actually prohibits it.