Bug 170071 [Undo] Undo deleting *.properties file sets explicit encoding
I20070109-1805 Create a *.properties file => Encoding is "Default (determined from content: ISO-8859-1)" Delete file in Navigator, the choose Edit > Undo => File is restored, but its encoding is now explicitly set to "ISO-8859-1"
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/undo/FileDescription.java
this.charset = null;
		this.fileContentDescription = fileContentDescription;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.internal.ide.undo.ResourceDescription#recordStateFromHistory(org.eclipse.core.resources.IResource,
	 *      org.eclipse.core.runtime.IProgressMonitor)
	 */
	public void recordStateFromHistory(IResource resource,
			IProgressMonitor monitor) throws CoreException {
		Assert.isLegal(resource.getType() == IResource.FILE);
		if (location != null) {
			
			return;
		}
		IFileState[] states = ((IFile) resource).getHistory(monitor);
		if (states.length > 0) {
			final IFileState state = getMatchingFileState(states);
			this.fileContentDescription = new IFileContentDescription() {
				/*
				 * (non-Javadoc)
				 * 
				 * @see org.eclipse.ui.internal.ide.undo.IFileContentDescription#exists()
				 */
				public boolean exists() {
					return state.exists();
				}
				/*
				 * (non-Javadoc)