How to reproduce:
1. Open the attached '1191820.zip' project
2. Open 'NewSurfaceShader.shader' shader
3. Notice that the number of keywords remains at 64
4. Replace 'x1' shader keyword to 'a1' shader keyword and save the shader

Expected result: Keywords are replaced and no error thrown to the Console
Actual result: Error is thrown to the Console that 'Maximum number (64) of shader local keywords exceeded, keyword x1 will be ignored.' and a keyword is discarded

Reproducible with: 2019.2.16f1, 2019.3.0f3
Not reproducible with: 2017.4.35f1, 2018.4.14f1, 2020.1.0a16

Notes:
- Screenshot and project of reproduction attached in Edit
- Local shader keywords are limited to 64 keywords per project while documentation states that it is limited to 64 keywords per shader. Any additional keyword is discarded.