Improve way cache version string is created (#19763)
Improve way cache version string is created (#19763)

Nitpicky change, but the version string contained a double `|`, implying that there might be an empty value between `process.env.__NEXT_VERSION` and the environment variables.
JeromeFitz/next.js,azukaru/next.js,JeromeFitz/next.js,flybayer/next.js,flybayer/next.js,zeit/next.js,azukaru/next.js,flybayer/next.js,JeromeFitz/next.js,azukaru/next.js,flybayer/next.js,JeromeFitz/next.js,zeit/next.js,azukaru/next.js,zeit/next.js