There is a difference in how 1.13.0 fetches using NPM and bower.

npm package contains backward-compatibility underscore.js file (underscore-umd copy, as confirmed with diff)

C:\Temp\teststs\node_modules\underscore (underscore@1.13.0)
λ ls -l underscore*.js
-rw-r--r-- 1 user 1049089 68420 Oct 26 1985 underscore.js
-rw-r--r-- 1 user 1049089 65946 Oct 26 1985 underscore-esm.js
-rw-r--r-- 1 user 1049089 25711 Oct 26 1985 underscore-esm-min.js
-rw-r--r-- 1 user 1049089 19530 Oct 26 1985 underscore-min.js
-rw-r--r-- 1 user 1049089 68420 Oct 26 1985 underscore-umd.js
-rw-r--r-- 1 user 1049089 19530 Oct 26 1985 underscore-umd-min.js

bower, fetching directly from github, does not contain underscore.js file, which genreally breaks a lot.

bower underscore#* new version forhttps://github.com/jashkenas/underscore.git#*
bower underscore#* resolvehttps://github.com/jashkenas/underscore.git#*
bower underscore#* downloadhttps://github.com/jashkenas/underscore/archive/1.13.0.tar.gz
1.13.0.tar.gz does not contain underscore.js

Is it expected behavior?