Single asterisk in my filters is not working anymore

[pkraskov]

Prerequisites

• I verified that this is not a filter issue
  • Filter issues MUST be reported at filter issue tracker
• This is not a support issue or a question
  • Support issues and questions are handled at /r/uBlockOrigin
• I performed a cursory search of the issue tracker to avoid opening a duplicate issue
  • Your issue may already be reported.
• I tried to reproduce the issue when...
  • uBlock Origin is the only extension
  • uBlock Origin with default lists/settings
  • using a new, unmodified browser profile
• I am running the latest version of uBlock Origin
• I checked the documentation to understand that the issue I report is not a normal behavior

Description

I don't use any filters except the only one asterisk "*" on My filters tab to archive the effect of blocking any site except manually whitelisted. After update to latest version I found that this functionality does not work anymore.
I did small research and found that the last version where it still works is 1.20.2.

A specific URL where the issue occurs

http://wikipedia.org/

Steps to Reproduce

1. uncheck all filters except My filters
2. put the only one character "*" in My filters tab
3. make sure you don't have whitelisted sites
4. try to open any site

Expected behavior:

Site should be blocked.

Actual behavior:

Site is not blocked.

Your environment

• uBlock Origin version: checked with 1.27.10, 1.21.0, 1.20.2 (works)
• Browser Name and version: Firefox 68.8.0esr 64-bit linux
• Operating System and version: Debian 9

[uBlock-user]

Duplicate of #687