[DRE-maint] Bug#979133: rails: build failure is silently ignored

[Pirate Praveen]

Package: rails
Version: 2:6.0.3.4+dfsg-2
Severity: serious

When I rebuilt all the packages during the rollup plugin transitions, 
rails did not ftbfs, even though the rollup command actually failed.

cd activestorage; mkdir node_modules; \
 ln -s rollup-plugin-commonjs node_modules; rollup -c; cd -
[!] Error: Cannot find module 'rollup-plugin-node-resolve'
Require stack:
- /<<PKGBUILDDIR>>/activestorage/rollup.config.js
- /usr/share/nodejs/rollup/dist/shared/loadConfigFile.js
- /usr/share/nodejs/rollup/dist/bin/rollup
Error: Cannot find module 'rollup-plugin-node-resolve'
Require stack:
- /<<PKGBUILDDIR>>/activestorage/rollup.config.js
- /usr/share/nodejs/rollup/dist/shared/loadConfigFile.js
- /usr/share/nodejs/rollup/dist/bin/rollup
    at Function.Module._resolveFilename 
(internal/modules/cjs/loader.js:831:15)
    at Function.Module._load (internal/modules/cjs/loader.js:687:27)
    at Module.require (internal/modules/cjs/loader.js:903:19)
    at require (internal/modules/cjs/helpers.js:74:18)
    at Object.<anonymous> 
(/<<PKGBUILDDIR>>/activestorage/rollup.config.js:5:15)
    at Module._compile (internal/modules/cjs/loader.js:1015:30)
    at Object.require.extensions.<computed> [as .js] 
(/usr/share/nodejs/rollup/cli/run/loadConfigFile.ts:91:38)
    at Module.load (internal/modules/cjs/loader.js:879:32)
    at Function.Module._load (internal/modules/cjs/loader.js:724:14)
    at Module.require (internal/modules/cjs/loader.js:903:19)