GCC master: Weird build problem on Fedora 29

[Dejan Lekic]

I am trying to build GCC master with D enabled, configured with:

../configure --enable-languages=d --prefix=/opt/gcc 
--mandir=/opt/gcc/share/man --infodir=/opt/gcc/share/info 
--enable-shared --enable-threads=posix --enable-checking=release 
--with-system-zlib --enable-multilib --with-tune=native 
--build=x86_64-redhat-linux

It stops at phobos:

Checking multilib configuration for libphobos...
Configuring in x86_64-redhat-linux/libphobos
configure: loading cache ./config.cache
checking build system type... x86_64-redhat-linux-gnu
checking host system type... x86_64-redhat-linux-gnu
checking target system type... x86_64-redhat-linux-gnu
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /usr/bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking whether make supports nested variables... yes
configure: error: source directory already configured; run "make 
distclean" there first
make[1]: *** [Makefile:19619: configure-target-libphobos] Error 1
make[1]: Leaving directory '/disk/one/src/gcc/build'
make: *** [Makefile:982: all] Error 2

When I do what it tells me to do (make distclean in the phobos 
directory) I am getting:

Making distclean in libdruntime
make[1]: Entering directory 
'/disk/one/src/gcc/libphobos/libdruntime'
make[1]: *** No rule to make target 'distclean'.  Stop.
make[1]: Leaving directory 
'/disk/one/src/gcc/libphobos/libdruntime'
make: *** [Makefile:468: distclean-recursive] Error 1

When I looked at libdruntime it seems like it was not configured 
properly (Makefile has not been generated):

dejan at turing$ ls
core  __entrypoint.di  gc  gcc  gcstub  LICENSE  __main.di  
Makefile.am  Makefile.in  object.d  rt