Bug 328879

After converting greyscale to RGB image, only 2 of the channels (Red and Green) are available in the Channels tab.

Reproducible: Always

Steps to Reproduce:
1. Open a greyscale image or create a B&W image.
2. Open channels tab and observe available channels (Gray and Alpha).
3. Use "Image/Convert Image Color Space" to convert image to RGB
4. Observe contents of "Channels" tab.


Actual Results:  
Shows only Red and Green selectors in the Channels tab.  Blue and Alpha channels are still available for painting.  They are simply not available in the Channels selector.

Expected Results:  
Should show selectors under the Channels tab for Red, Green, Blue and Alpha.

This appears to be a general problem with image conversion.  Whatever number of channels were allocated when the image was created or loaded will be the number available when the image is converted (example: Converting an RGB image to CMYK shows only the CMY and K channels, with no alpha.  Converting to greyscale correctly reduces the number of channels to Gray and Alpha, but converting back to CMYK still only shows 4 channels.).