As a workaround the package can be installed using "MAKEOPTS=-j1 emerge netcdf".
Created attachment 211202 [details] build.log
I do not observe this. Please attach build log and your emerge --info.
Created attachment 212315 [details] emerge --info build.log already attached. I do not think emerge --info will help much, but here you go.
I've just committed a revised 3.6.3 ebuild that uses the same trick for parallel building when the doc flag is on as in the 4.0.1. If it still fails for you, re-open. Thanks.