gentoo compile error at running automake

Sometimes we may have error when build some package, the error message may liike:

>>> Emerging (1 of 1) media-gfx/graphviz-2.26.3-r3
* graphviz-2.26.3.tar.gz RMD160 SHA1 SHA256 size ;-) ...                [ ok ]
>>> Unpacking source...
>>> Unpacking graphviz-2.26.3.tar.gz to /var/tmp/portage/media-gfx/graphviz-2.26                                                                                                                           .3-r3/work
>>> Source unpacked in /var/tmp/portage/media-gfx/graphviz-2.26.3-r3/work
>>> Preparing source in /var/tmp/portage/media-gfx/graphviz-2.26.3-r3/work/graphviz-2.26.3 ...
* Applying graphviz-2.26.3-libtool.patch ...                            [ ok ]
* Running eautoreconf in '/var/tmp/portage/media-gfx/graphviz-2.26.3-r3/work/graphviz-2.26.3' ...
* Running aclocal -I m4 ...                                             [ ok ]
* Running libtoolize --copy --force --automake ...                      [ ok ]
* Running aclocal -I m4 ...                                             [ ok ]
* Running autoconf ...                                                  [ ok ]
* Running autoheader ...                                                [ ok ]
* Running automake --add-missing --copy ...                             [ !! ]

* Failed Running automake !
*
* Include in your bugreport the contents of:
*
*   /var/tmp/portage/media-gfx/graphviz-2.26.3-r3/temp/automake.out

* ERROR: media-gfx/graphviz-2.26.3-r3 failed (prepare phase):
*   Failed Running automake !

This may caused by automake version is incorrect (IE: automake too new), we can set automake version by export WANT_AUTOMAKE environment variable:

WANT_AUTOMAKE=1.10 emerge -1av graphviz

For details, please see file /usr/lib64/misc/am-wrapper.sh