After investigations, commit the proposed patch by kklimonda presented with the following introduction : cm/templates/site/login_form.html template uses a relative url for the form action, which seems to break deployment in the subfolder when trailing slash is missing (the form redirects to the upper folder breaking login). Using {% url login %} (as in the attached patch) instead would fix the issue.

src.dir = src
lib.dir = lib
doc.dir = doc
build.dir = build
product.name = yuicompressor
version.number = 2.4.2
jar.name = ${product.name}-${version.number}.jar
dist.package.name = ${product.name}-${version.number}