This patch comes from in-house and has been submitted upstream:
http://savannah.gnu.org/bugs/?44018

--- groff-1.22.2/src/roff/troff/env.cpp.org	2013-02-07 21:06:06.000000000 +0900
+++ groff-1.22.2/src/roff/troff/env.cpp	2015-01-14 10:23:07.817142586 +0900
@@ -2110,6 +2110,9 @@
     }
     distribute_space(pre, bp->nspaces, extra_space_width);
     hunits output_width = bp->width + extra_space_width;
+    if (output_width <= 0)
+      return;
+
     input_line_start -= output_width;
     if (bp->hyphenated)
       hyphen_line_count++;