A new visit is created on the Database when changing the userId field from the Android-SDK

[ghost]

The first event fired from the native Android-SDK after setting a new userId creates a new Visit in the Piwik Database.
This occurs only when the User-Agent is the one generated by the Android-SDK. If I try to send the same request with the user-agent generated by the Android Chrome app or the iOS SDK a new visit is not created.

To recreate this behavior:

1. Send a request with no uid parameter and this User-Agent:
   Dalvik/2.1.0 (Linux; U; Android 7.1.2; Nexus 6P Build/N2G48B)
2. Send a request with a uid and the same User-Agent
3. Notice the new visit at the log_visit table.

Does this behavior has anything to do with issue number #7691?

Thanks