diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -121,7 +121,7 @@
     'rsrc/css/fuel/fuel-handle-list.css' => '2c4cbeca',
     'rsrc/css/fuel/fuel-map.css' => 'd6e31510',
     'rsrc/css/fuel/fuel-menu.css' => '21f5d199',
-    'rsrc/css/layout/phabricator-source-code-view.css' => '49656486',
+    'rsrc/css/layout/phabricator-source-code-view.css' => 'e382316a',
     'rsrc/css/phui/button/phui-button-bar.css' => 'a4aa75c4',
     'rsrc/css/phui/button/phui-button-simple.css' => '1ff278aa',
     'rsrc/css/phui/button/phui-button.css' => 'f9d0f9c8',
@@ -805,7 +805,7 @@
     'phabricator-search-results-css' => '9ea70ace',
     'phabricator-shaped-request' => '995f5102',
     'phabricator-slowvote-css' => '1694baed',
-    'phabricator-source-code-view-css' => '49656486',
+    'phabricator-source-code-view-css' => 'e382316a',
     'phabricator-standard-page-view' => 'e08c7462',
     'phabricator-textareautils' => 'f340a484',
     'phabricator-title' => '43bc9360',
diff --git a/src/applications/diffusion/request/DiffusionMercurialRequest.php b/src/applications/diffusion/request/DiffusionMercurialRequest.php
--- a/src/applications/diffusion/request/DiffusionMercurialRequest.php
+++ b/src/applications/diffusion/request/DiffusionMercurialRequest.php
@@ -3,6 +3,9 @@
 final class DiffusionMercurialRequest extends DiffusionRequest {
 
   protected function isStableCommit($symbol) {
+    if ($symbol === null) {
+      return false;
+    }
     return preg_match('/^[a-f0-9]{40}\z/', $symbol);
   }
 
@@ -10,11 +13,9 @@
     if ($this->branch) {
       return $this->branch;
     }
-
     if ($this->repository) {
       return $this->repository->getDefaultBranch();
     }
-
     throw new Exception(pht('Unable to determine branch!'));
   }
 
diff --git a/src/applications/diffusion/request/DiffusionSvnRequest.php b/src/applications/diffusion/request/DiffusionSvnRequest.php
--- a/src/applications/diffusion/request/DiffusionSvnRequest.php
+++ b/src/applications/diffusion/request/DiffusionSvnRequest.php
@@ -3,6 +3,9 @@
 final class DiffusionSvnRequest extends DiffusionRequest {
 
   protected function isStableCommit($symbol) {
+    if ($symbol === null) {
+      return false;
+    }
     return preg_match('/^[1-9]\d*\z/', $symbol);
   }
 
diff --git a/webroot/rsrc/css/layout/phabricator-source-code-view.css b/webroot/rsrc/css/layout/phabricator-source-code-view.css
--- a/webroot/rsrc/css/layout/phabricator-source-code-view.css
+++ b/webroot/rsrc/css/layout/phabricator-source-code-view.css
@@ -16,7 +16,7 @@
   white-space: pre-wrap;
   padding: 2px 8px 1px;
   width: 100%;
-  background: #ffffff;
+  background: {$diff.background};
 }
 
 .phabricator-source-line {