[Libguestfs] installing appears broken by 199f218bf431b77c12a728f7072bed1553a0f0af

[Nix]

The intent of commit 199f218bf431b77c12a728f7072bed1553a0f0af seems
praiseworthy, but since 'all-am' is automatically added by Automake as a
prerequisite of the 'install' target, its effect is to stop people
running 'make install' as root:

make  install-am
make[2]: Entering directory `/usr/src/libguestfs/x86_64-spindle/src'
make -C ../generator stamp-generator
make[3]: Entering directory `/usr/src/libguestfs/x86_64-spindle/generator'
make[3]: `stamp-generator' is up to date.
make[3]: Leaving directory `/usr/src/libguestfs/x86_64-spindle/generator'
*** Error: Don't run 'make' or 'make check' as root.
make[2]: *** [checkroot] Error 1
make[2]: Leaving directory `/usr/src/libguestfs/x86_64-spindle/src'
make[1]: *** [install] Error 2
make[1]: Leaving directory `/usr/src/libguestfs/x86_64-spindle/src'
make: *** [install-recursive] Error 1

This seems... counterintuitive. Was that really the intent of this
change?

(And how did nobody notice it? I'm using Automake 1.11.1, but Automake
has done this for a long, long time.)