* Package:    dev-util/promu-0.2.0
 * Repository: gentoo
 * Maintainer: mrueg@gentoo.org
 * USE:        abi_x86_64 amd64 elibc_glibc kernel_linux userland_GNU
 * FEATURES:   network-sandbox preserve-libs sandbox userpriv usersandbox
>>> Unpacking source...
>>> Source unpacked in /var/tmp/portage/dev-util/promu-0.2.0/work
>>> Preparing source in /var/tmp/portage/dev-util/promu-0.2.0/work/promu-0.2.0 ...
>>> Source prepared.
>>> Configuring source in /var/tmp/portage/dev-util/promu-0.2.0/work/promu-0.2.0 ...
>>> Source configured.
>>> Compiling source in /var/tmp/portage/dev-util/promu-0.2.0/work/promu-0.2.0 ...
/var/tmp/portage/dev-util/promu-0.2.0/work/promu-0.2.0/src/github.com/prometheus/promu /var/tmp/portage/dev-util/promu-0.2.0/work/promu-0.2.0
make -j1 build 
Makefile:19: warning: overriding recipe for target 'promu'
Makefile.common:106: warning: ignoring old recipe for target 'promu'
GOOS= GOARCH= go install github.com/prometheus/promu
failed to initialize build cache at /root/cache/go-build: mkdir /root/cache: permission denied
make: *** [Makefile:19: promu] Error 1
 * ERROR: dev-util/promu-0.2.0::gentoo failed (compile phase):
 *   emake failed
 * 
 * If you need support, post the output of `emerge --info '=dev-util/promu-0.2.0::gentoo'`,
 * the complete build log and the output of `emerge -pqv '=dev-util/promu-0.2.0::gentoo'`.
 * The complete build log is located at '/var/log/portage/dev-util:promu-0.2.0:20190227-192142.log'.
 * For convenience, a symlink to the build log is located at '/var/tmp/portage/dev-util/promu-0.2.0/temp/build.log'.
 * The ebuild environment file is located at '/var/tmp/portage/dev-util/promu-0.2.0/temp/environment'.
 * Working directory: '/var/tmp/portage/dev-util/promu-0.2.0/work/promu-0.2.0/src/github.com/prometheus/promu'
 * S: '/var/tmp/portage/dev-util/promu-0.2.0/work/promu-0.2.0'