It happened to me several times that I forgot to import eutils in an ebuild file. However, emerge silently continued. See example below of one such case. >>> Emerging (1 of 1) sci-biology/repeatmasker-4.0.1-r1::science * RepeatMasker-open-4-0-1.tar.gz SHA256 SHA512 WHIRLPOOL size ;-) ... [ ok ] >>> Unpacking source... >>> Unpacking RepeatMasker-open-4-0-1.tar.gz to /var/tmp/portage/sci-biology/repeatmasker-4.0.1-r1/work >>> Source unpacked in /var/tmp/portage/sci-biology/repeatmasker-4.0.1-r1/work >>> Preparing source in /var/tmp/portage/sci-biology/repeatmasker-4.0.1-r1/work/RepeatMasker ... /var/tmp/portage/sci-biology/repeatmasker-4.0.1-r1/temp/environment: line 265: epatch: command not found >>> Source prepared. ^C # emerge --info Portage 2.2.18 (python 2.7.10-final-0, default/linux/amd64/13.0, gcc-4.9.3, glibc-2.21-r1, 4.3.0-rc7-default-pciehp x86_64) ================================================================= System uname: Linux-4.3.0-rc7-default-pciehp-x86_64-Intel-R-_Core-TM-_i7-2640M_CPU_@_2.80GHz-with-gentoo-2.2 KiB Mem: 16361256 total, 10656584 free KiB Swap: 16776188 total, 16776188 free Timestamp of repository gentoo: Mon, 23 Nov 2015 12:30:01 +0000 sh bash 4.3_p42 ld GNU ld (Gentoo 2.25.1 p1.1) 2.25.1 app-shells/bash: 4.3_p42::gentoo dev-java/java-config: 2.2.0::gentoo dev-lang/perl: 5.20.2-r1::gentoo dev-lang/python: 2.7.10::gentoo, 3.4.3::gentoo dev-util/cmake: 3.3.2-r1::gentoo dev-util/pkgconfig: 0.28-r2::gentoo sys-apps/baselayout: 2.2::gentoo sys-apps/openrc: 0.18.3::gentoo sys-apps/sandbox: 2.6-r1::gentoo sys-devel/autoconf: 2.13::gentoo, 2.69-r1::gentoo sys-devel/automake: 1.11.6-r1::gentoo, 1.12.6::gentoo, 1.13.4::gentoo, 1.14::gentoo, 1.15::gentoo sys-devel/binutils: 2.25.1-r1::gentoo sys-devel/gcc: 4.3.6-r1::gentoo, 4.4.7::gentoo, 4.6.4::gentoo, 4.7.4::gentoo, 4.8.5::gentoo, 4.9.3::gentoo sys-devel/gcc-config: 1.8::gentoo sys-devel/libtool: 2.4.6-r1::gentoo sys-devel/make: 4.1-r1::gentoo sys-kernel/linux-headers: 4.0::gentoo (virtual/os-headers) sys-libs/glibc: 2.21-r1::gentoo
This can happen for any eclass function. A nice solution would be to enable 'set -e' by default, but that idea has been rejected (see bug 138792). Note that repoman checks for epatch calls with missing eutils inherit (among other things).
(In reply to Zac Medico from comment #1) the eclass checks were disabled by default a long time ago and i doubt anyone enables them by hand