v0.9.0

Minor Changes

• a8bffa5: /health's environment carries windowsBuild, "<build>.<ubr>" (for example 26100.4652), read from the registry's CurrentBuild and UBR under HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion. windowsVersion is Win32_OperatingSystem.Version and does not move when a monthly cumulative update lands, so two boxes one update apart read the same; the revision does. It is a NEW field and windowsVersion is unchanged, because windowsVersion is half of the capture cache's os key and appending the revision to it would invalidate every cached capture. windowsBuild is not in any key. It is sampled on the same timer tick as windowsVersion, never on the request path, and an unreadable or half-read value (a key without UBR) reports "unknown". The fleet reports it as REPORTED_ONLY first, and it graduates to MUST_MATCH once the fleet reads one value (#4405).