Cannot create offline source tarball on ufs-v2.0.0 branch

[maddenp]

Describe the bug
cmake -DDOWNLOAD_ONLY=ON . as described in README.md on the ufs-v2.0.0 branch does not work. A netCDF installation is demanded. If pointed to a netCDF installation, an ESMF installation is then demanded. netCDF and ESMF should not be required to download source code. This problem doesn't exist on the develop branch, but the contents of the download directory that branch creates differ from what is downloaded on ufs-v2.0.0 when, by pre-building netCDF and ESMF, the sources can finally be downloaded.

To Reproduce
Unrelated output elided:

git clone https://github.com/NOAA-EMC/NCEPLIBS.git
cd NCEPLIBS
git checkout ufs-v2.0.0
cmake -DDOWNLOAD_ONLY=ON .
...
CMake Error at CMakeLists.txt:259 (find_package):
  By not providing "FindNetCDF.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "NetCDF", but
  CMake did not find one.
...

Expected behavior
Source is downloaded as it is on the develop branch.

System
Linux

Additional context
A workaround for me would be to download the source on the develop branch, but I would need to know that it satisfies the requirements of the code on the ufs-v2.0.0 branch.

[edwardhartnett]

A better workaround it to download and install the libraries separately.

We are moving to a spack-based distribution, and the NCEPLIBS project will be retired...