Do not overwrite secret token value when already present.

```
user = User.create(token: "custom-secure-token")
user.token # => "custom-secure-token"
```

1 files changed, 1 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/secure_token.rb b/activerecord/lib/active_record/secure_token.rb
index 07031b6371..0990f815a7 100644
--- a/activerecord/lib/active_record/secure_token.rb
+++ b/activerecord/lib/active_record/secure_token.rb
@@ -27,7 +27,7 @@ module ActiveRecord
         # Load securerandom only when has_secure_token is used.
         require 'active_support/core_ext/securerandom'
         define_method("regenerate_#{attribute}") { update! attribute => self.class.generate_unique_secure_token }
-        before_create { self.send("#{attribute}=", self.class.generate_unique_secure_token) }
+        before_create { self.send("#{attribute}=", self.class.generate_unique_secure_token) unless self.send("#{attribute}?")}
       end
 
       def generate_unique_secure_token
@@ -36,4 +36,3 @@ module ActiveRecord
     end
   end
 end
-