serf-0.7.0 build failure in libtool

[wp@…]

The log :

:info:build /opt/local/share/apr-1/build/libtool: line 819: /opt/local/bin/echo: No such file or directory
:info:build /opt/local/share/apr-1/build/libtool: line 821: /opt/local/bin/echo: No such file or directory
:info:build /opt/local/share/apr-1/build/libtool: line 819: /opt/local/bin/echo: No such file or directory
:info:build /opt/local/share/apr-1/build/libtool: line 755: /opt/local/bin/echo: No such file or directory
:info:build /opt/local/share/apr-1/build/libtool: line 821: /opt/local/bin/echo: No such file or directory
:info:build make: *** [buckets/request_buckets.lo] Error 1
:info:build make: *** Waiting for unfinished jobs....
:info:build /opt/local/share/apr-1/build/libtool: line 755: /opt/local/bin/echo: No such file or directory
:info:build make: *** [buckets/aggregate_buckets.lo] Error 1
:info:build shell command " cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_www_serf/work/serf-0.7.0" && /usr/bin/make -j2 all " returned error 2
:error:build Target org.macports.build returned: shell command failed (see log for details)
:debug:build Backtrace: shell command failed (see log for details)
    while executing
"command_exec build"
    (procedure "portbuild::build_main" line 8)
    invoked from within
"$procedure $targetname"
:info:build Warning: the following items did not execute (for serf): org.macports.activate org.macports.build org.macports.destroot org.macports.install
:notice:build Log for serf is at: /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_ports_www_serf/main.log

the fix :

sudo ln -s /opt/local/libexec/gnubin/echo /opt/local/bin