The commit comment form doesn't always appear when saving a job configuration. The fault seems to lie in the PageMatcher regexp.

I've tested the current regexp against a couple of different URIs:
"view/x//job/a/configure" Passed
"view/x//job/a/job/b/configure" Passed
"view/x//job/a/job/b/job/c/configure" Passed
"/job/a/configure" Passed
"/job/a/job/b/configure" Passed
"/view/x//job/a/job/b/job/c/configure" Passed
"view/x/job/a/job/b/configure" Failed!
"/job/ab/job/b/configure" Failed!
"view/x/job/a/configure" Failed!
"/view/x/job/a/configure" Failed!
"job/a/configure" Failed!
"///view/////x//job//a//job//b/////job//c//configure" Failed!

Some of the failed URIs are real-life examples of URIs where the commit comment form doesn't appear, others are more hypothetical.

I can work around the problem by adding an extra slash to my URIs when I configure jobs. Instead of opening view/All/job/myjob/configure in my browser, I open view/All//job/myjob/configure.