*** [installworld] Stopped -- signal 22

[bob prohaska]

The past three attempts at an 11-CURRENT build install cycle self-hosted on 
an rpi2 have stopped immediately in installworld with the message:

*** [installworld] Stopped -- signal 22

World and kernel builds report successful completion. The running system is
at r293117, the source tree is three days newer. Svnlite status reports no
modified files. The buildscript normally runs in the background and the log
files indicate a prompt failure. If make installworld is run in the foreground
the console session seems to hang and top shows make instances, but none use 
cpu time. Control-C terminates the make without any messages.

All storage except the microSD card is on a mechanical hard disk.

The previous dozen build/install cycles worked without trouble,
any guidance appreciated!

Thanks for reading,

bob prohaska