Two latent bugs in the release pipeline that conspired to ship a stale
linux-x64 binary in 0.27.0-fork.5 (only caught by manually grepping
the embedded version string):
1. build-linux ran x64 and arm64 in parallel and used a single
`wait $PID1 $PID2` to join them. That command waits for both, but
its exit code is the LAST waited pid only — so if x64 silently
broke and arm64 succeeded, the outer script exited 0 and shipped
whatever was already in /output from the previous release. Now we
wait on each pid individually and exit 1 on either failure.
2. build-single's cp used `agent-browser*` which globs to BOTH the
binary and its `.d` dependency file. When two sources are passed,
cp requires the destination to be a directory. We weren't, so cp
exited non-zero with "Not a directory" and the build script
shrugged it off because the next line was `chmod ... || true`.
Now we resolve a single explicit source path.
leeguooooo