Fix issue processwire/processwire-issues#1805

wire/modules/Fieldtype/FieldtypePage.module

@@ -1326,6 +1326,27 @@ class FieldtypePage extends FieldtypeMulti implements Module, ConfigurableModule
 		return true;
 	}
 
+	/**
+	 * Return whether the given value is considered empty or not.
+	 *
+	 * @param Field $field
+	 * @param mixed|Selector $value
+	 * @return bool
+	 *
+	 */
+	public function isEmptyValue(Field $field, $value) {
+		if($value instanceof Selector && $value->field === $field->name) {
+			// PageFinder is asking if we want to handle this field/value match internally
+			if($value->operator === '!=' && !empty("$value->value") && !ctype_digit("$value->value")) {
+				// if a page name (rather than id) is specified with a `!=` operator
+				// then tell PageFinder that we handle this unique match condition internally
+				// since the page name has to be converted to page ID by getMatchQuery()
+				return true;
+			}
+		}
+		return parent::isEmptyValue($field, $value);
+	}
+	
 	/**
 	 * Return the database schema in predefined format 
 	 *