gimp3-devel non-X11 depends on both babl and babl-devel, which conflict

[andlabs (Pietro Gagliardi)]

According to macports_deptree output, gimp3-devel +quartz -x11 +no_x11 depends on both babl-devel and gegl-devel, and gegl-devel depends on babl; installing gimp3-devel therefore tries to install both babl and babl-devel, which are conflicting packages. This causes installation to fail:

$ sudo port install gimp3-devel +quartz -x11 +no_x11
--->  Computing dependencies for gimp3-devel
The following dependencies will be installed: 
 babl
 babl-devel
 gegl-devel
Continue? [Y/n]: 
--->  Fetching archive for babl-devel
--->  Attempting to fetch babl-devel-0.1.102_0.darwin_16.x86_64.tbz2 from https://packages.macports.org/babl-devel
--->  Attempting to fetch babl-devel-0.1.102_0.darwin_16.x86_64.tbz2.rmd160 from https://packages.macports.org/babl-devel
--->  Installing babl-devel @0.1.102_0
--->  Activating babl-devel @0.1.102_0
--->  Cleaning babl-devel
--->  Fetching archive for babl
--->  Attempting to fetch babl-0.1.102_0.darwin_16.x86_64.tbz2 from https://packages.macports.org/babl
--->  Attempting to fetch babl-0.1.102_0.darwin_16.x86_64.tbz2.rmd160 from https://packages.macports.org/babl
--->  Installing babl @0.1.102_0
--->  Activating babl @0.1.102_0
Error: Failed to activate babl: Image error: /opt/local/bin/babl is being used by the active babl-devel port.  Please deactivate this port first, or use 'port -f activate babl' to force the activation.
    while executing
"throw registry::image-error $msg"
    ("foreach" body line 47)
    invoked from within
"foreach file $imagefiles {
                set srcfile "${extracted_dir}${file}"

                # To be able to install links, we test if we can lst..."
    invoked from within
"registry::write {
            foreach file $imagefiles {
                set srcfile "${extracted_dir}${file}"

                # To be able to instal..."
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_macports_release_tarballs_ports_graphics_babl/babl/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets if you believe there
is a bug.
Error: Processing of port gimp3-devel failed

This is on macOS 10.12.