To reproduce, deploy myapp.zip along Orbeon Forms. Notice how, with:
+1 from community
Curiously, both works for me with Apache Tomcat/7.0.68. @avernet used Tomcat/8.0.33.
With a stock 2016.1.201604200638-PE release, it works for me with Tomcat 7.0.68, but not Tomcat 8.0.21.
Findings so far:
Making progress by comparing the CoyoteOutputStream in both cases:
Fix #2775 "Separate deployment: content "cut" with .html"
Attaching the screenshots for reference.