A delivery that replaced mesh-build-go left a check ask's key running, and
the new process's start sweep spared it as an ask younger than the step
bound, so it held a build slot until a hand end (issue 1890, note 21).
Each step now records its owner (boot id, pid, process start); the sweep
ends a running step of another owner at once and says its owner, while a
key with no owner keeps the earlier rule. The conformance kit gains the
left-running case every build module runs through its own start sweep.
Each build module parsed its own test runner's output, so a fix in one never reached the others: a failed node --test
run was worded by a passing line of its first file. buildstep.Failure names the test, its file, its cause and its own
output; ReadGoTest (moved from mesh-build-go) and ReadTAP fill it; package conformance holds every build module to it
with runner output captured with the build nodes' own toolchains.