Fix upperCaseUsername check

The string equality check was wrongly performed against the replacement
string instead of against the placeholder.

Change-Id: I12c01e185dd7919ff748d8180c86d6deb4437396

src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java b/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
index b2da42b..34b41e6 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
@@ -115,7 +115,7 @@
     if (url == null || replacement == null || !url.contains(placeholder)) {
       return url;
     }
-    if ("${user}".equals(replacement) && upperCaseUsername) {
+    if ("${user}".equals(placeholder) && upperCaseUsername) {
       replacement = replacement.toUpperCase();
     } else if (lowerCase) {
       replacement = replacement.toLowerCase();