Error during bootstrap while building Julia 1.2 on macOS Mojave

While building Julia 1.2 on macOS Mojave, I get an error during bootstrap:

$ git checkout release-1.2
Already on 'release-1.2'
Your branch is up to date with 'origin/release-1.2'.
$ make
error during bootstrap:
LoadError("sysimg.jl", 16, LoadError("JULIA_DIRECTORY/usr/share/julia/stdlib/v1.2/SuiteSparse/src/SuiteSparse.jl", 24, LoadError("JULIA_DIRECTORY/usr/share/julia/stdlib/v1.2/SuiteSparse/src/umfpack.jl", 66, ErrorException("error compiling top-level scope: could not load library \"libsuitesparse_wrapper\"\ndlopen(libsuitesparse_wrapper.dylib, 1): Library not loaded: @rpath/libgfortran.5.dylib\n  Referenced from: JULIA_DIRECTORY/usr/lib/./libopenblas64_.0.3.5.dylib\n  Reason: image not found"))))

where JULIA_DIRECTORY refers to the directory where the Julia repository is cloned.

It seems that make is trying to use libgfortran.5.dylib which came with my brew-installed GCC 9, though OpenBLASBuilder uses libgfortran.4.dylib, as discussed in this issue: I had a similar problem when I tried to build Arpack.jl, and I was able to solve the issue by installing GCC 7 and pointing DYLD_LIBRARY_PATH to the directory where libgfortran.4.dylib that came with libgfortran.4.dylib exists. The same trick doesn’t work for the present problem.

Is there any method to work around this issue and build Julia 1.2? It seems that this issue has been fixed in the later versions of Julia; I can build the master branch successfully (version 1.4.0-DEV.142).