Source lookup in .changes file fails in headless mode on Linux

We have a problem with the Seaside tests in Squeak 5.1. The underlying issue is that source code lookup fails in headless mode on Linux (not reproducible on macOS). To reproduce evaluate in headless mode:

Object compile: 'foobar ^ [ 1+ 2] value "blah"'. (Object>>#foobar) getSourceFromFileAt: (Object>>#foobar) trailer sourcePointer.

This will signal an error (RemoteString past end of file). (Note: I checked the alternative conditions in CompiledMethod>>#getSource: the method trailer has no temp names, no #source property but has a source pointer).

I would appreciated it if someone would look into this.

Cheers,

Max

Environment:

Ubuntu 14.04 and 17.04

32-bit