Crash in Make 3.79.1 expanding target specific variables

[Robert Bogomip]

[This is actually a repost of a bug that previously had been fixed :-(]

There's (still) a problem expanding target specific variables.

Consider this makefile:

  t: m+=2

  t:
        @echo "[${m}]"

Then the following displays a bugette:

  $ make t
  [ 2]
  $

[That space shouldn't be there.] BUT the folowing crashes:

  $ make m=blah
  make: expand.c:489: allocated_variable_append: Assertion 
`current_variable_set_list->next != 0' failed.
  Aborted (core dumped)
  $

This crashes on all versions of 3.79.1 that I can find (SuSE, Red Hat, cygwin,
mingw...)

--
Robert Bogomip /// mailto:bob.bogo :at: milohedge.com
Milo Hedge Ltd, OCFI, Mill Street, Oxford, OX2 0JX /// tel:+44 1865 799400