Image copy error

Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=3153

Reported by Martin Stjernholm mast@roxen.com

I get a lot of errors like these when I run the refdoc extractor in a spotless tree:

Extracting file "../src/post_modules/GTK/refdoc/GTK.pmod/Button.pike"...
copying from

[/home/mast/Pike/7.3/refdoc/build/src/post_modules/GTK/refdoc/images/gtk_button.png] to [build/images//GTK.Button.1.png] Error: Could not move /home/mast/Pike/7.3/refdoc/build/src/post_modules/GTK/refdoc/images/gtk_button.png to build/images//GTK.Button.1.png. (Could not read /home/mast/Pike/7.3/refdoc/build/src/post_modules/GTK/refdoc/images/gtk_button.png) copying from [/home/mast/Pike/7.3/refdoc/build/src/post_modules/GTK/refdoc/images/gtk_button_2.png] to [build/images//GTK.Button.2.png] Error: Could not move /home/mast/Pike/7.3/refdoc/build/src/post_modules/GTK/refdoc/images/gtk_button_2.png to build/images//GTK.Button.2.png. (Could not read /home/mast/Pike/7.3/refdoc/build/src/post_modules/GTK/refdoc/images/gtk_button_2.png)

Note that it tries to copy from the build directory. At the point when it complains, the images doesn't there, and neither does the images directory. Afterwards all files seems to be there.