mkversion derives the version from git history, which a shallow clone
lacks (the change count silently comes out as 0) and a tree without
.git can't provide at all. If TS_VERSION_LONG is set, InfoFrom now
takes the version from it plus TS_VERSION_GIT_HASH (and the EXTRA/DATE
variants), runs no git, and derives everything else through the same
mkOutput as the git path. The result's Long must reproduce the input
exactly or InfoFrom errors.
Updates tailscale/corp#44945
Change-Id: I9c1247ea5d1c6c52c823c2205447b5c7ee8e778c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Brad Fitzpatrick
70422c917a