"No results for "x"" text in the Package Manager Search is not updated when edited search string has no matches as well

How to reproduce:
1. Create a new Unity project
2. Go to Window -> Package Management -> Package Manager
3. In the search, enter any string that doesn't have matches
4. Update the string to have no matches too
5. Observe the results

Expected results: "No results for "x"" shows the last entered string
Actual results" "No results for "x"" shows the first string that didn't return anything

Reproducible with: 6000.5.0a8, 6000.5.0b8, 6000.6.0a6
Not reproducible with: 6000.0.76f1, 6000.4.8f1, 6000.5.0a7

Note: Sometimes the text is updated mid entering the string