Getting context of another webapp in tomcat

I have the following configuration running on Tomcat 8.0.20:

C:\tomcat
   conf
     server.xml
     context.xml
   webapps
     app
     app2
   ......
C:\external
     app3
        web
     app4
        web
     app5
        web

In context.xml I have <Context crossContext="true"> .... </Context>

And in server.xml:

 ..........
 <Host name="host.com"  appBase="webapps" unpackWARs="true" autoDeploy="true">
    <Context 
      cachingAllowed="false"
      docBase="C:\external\app3\web" 
      path="" 
      crossContext="true"
      reloadable="true" />

    <Context 
      cachingAllowed="false"
      crossContext="true"
      docBase="C:\external\app4\web" 
      path="/app4"
      reloadable="true" />

    <Context 
      cachingAllowed="false"
      crossContext="true"
      docBase="C:\external\app5\web" 
      path="/app5"
      reloadable="true" />
 </Host>

Obtaining the Context of /app, /app2 or /app5 from /app4 works as espected:

request.getServletContext().getContext("/app") is not null.

However, requesting the Context of /app3 (with context path /).

Any idea why getContext("/") is null?

As it turned out, it's a regression in tomcat after version 8.0.15

Filed a bug report here

Reverted tomcat to 8.0.15 and it's working now....