make footer border color use header border color in modals

customize.html

@@ -1033,12 +1033,12 @@ lead: Customize Bootstrap's components, LESS variables, and jQuery plugins to ge
           <label>@modal-content-fallback-border-color</label>
           <input type="text" placeholder="#999">
           <p class="help-block">Modal content border color <strong>for IE8</strong></p>
-        </div> 
+        </div>
         <div class="col-lg-4">
           <label>@modal-backdrop-bg</label>
           <input type="text" placeholder="#000">
           <p class="help-block">Modal backdrop background color</p>
-        </div> 
+        </div>
         <div class="col-lg-4">
           <label>@modal-header-border-color</label>
           <input type="text" placeholder="#e5e5e5">
@@ -1046,9 +1046,9 @@ lead: Customize Bootstrap's components, LESS variables, and jQuery plugins to ge
         </div>
         <div class="col-lg-4">
           <label>@modal-footer-border-color</label>
-          <input type="text" placeholder="#e5e5e5">
+          <input type="text" placeholder="@modal-header-border-color">
           <p class="help-block">Modal footer border color</p>
-        </div>  
+        </div>
       </div>
 
       <h2 id="variables-carousel">Carousel</h2>

less/variables.less

@@ -301,10 +301,9 @@
 @modal-content-fallback-border-color:          #999;
 
 @modal-backdrop-bg:           #000;
-
 @modal-header-border-color:   #e5e5e5;
+@modal-footer-border-color:   @modal-header-border-color;
 
-@modal-footer-border-color:   #e5e5e5;
 
 // Alerts
 // -------------------------