Hadrian's stdout/stderr capture can capture unbounded output
Hadrian.Builder.cmd' utility used by Hadrian to run builders forces capture of
stderr. These are apparently buffered in memory. This can easily backfire if faced with a process that emits a large quantity of output (e.g. GHC with dump flags or even the testsuite driver with some test failures).
We should either:
- disable this behavior by default,
- bound the quantity of output that we collect, or
- buffer to file instead of in memory