Steps to reproduce the problem:
1. Connect to an Android device/emulator using Appium.
2. Using Selenium, create a cookie whose name starts with "session", like "session-id" or "session-very-long-name", or just "session".
3. Using Selenium, delete that cookie.

Code to reproduce (need to have Appium and device/emulator running): https://github.com/MicahLC/android_session_cookie_bug

What is the expected behavior?
Cookie is deleted without error.

What went wrong?
Get the following error in Selenium: An unknown server-side error occurred while processing the command. Original error: Could not proxy. Proxy error: Could not find :session section for url: /session2-id-longer-really-long-name (WARNING: The server did not provide any stacktrace information)

Did this work before? N/A 

Chrome version: 58.0.3029  Channel: stable
OS Version: OS X 10.12.6
Flash Version: 

This works without error on all desktop browsers I've tried.

I included code to reproduce the problem in the repo steps above, but I'll include the link here, too: https://github.com/MicahLC/android_session_cookie_bug

I'm creating this issue because the maintainers of Appium told me to here: https://github.com/appium/appium/issues/11052#issuecomment-405486780