[rt46602] Escape line ends in shell script variable assignment

[rt46602] Escape line ends in shell script variable assignment

Escape the line ends in a multi-line variable assignment.  Under some
circumstances, substituting the variable caused syntax errors when
used as the list of values in a shell script "for" statement.

(cherry picked from commit 462766cd763413c4a0d069b7adf2e65816851493)
(cherry picked from commit 53ebdf225f9389ef8128d273230865e496787dba)
(cherry picked from commit 82ffebc73a8886a25f692b93684d66d8fcfd49f5)