patch 8.0.0533: abbreviation doesn't work after backspacing newline

Problem:    Abbreviation doesn't work after backspacing newline. (Hkonrk)
Solution:   Set the insert start column. (closes #1609)

src/edit.c

@@ -9017,7 +9017,7 @@ ins_bs(
 #endif
 
     /*
-     * delete newline!
+     * Delete newline!
      */
     if (curwin->w_cursor.col == 0)
     {
@@ -9032,7 +9032,7 @@ ins_bs(
 			       (linenr_T)(curwin->w_cursor.lnum + 1)) == FAIL)
 		return FALSE;
 	    --Insstart.lnum;
-	    Insstart.col = MAXCOL;
+	    Insstart.col = STRLEN(ml_get(Insstart.lnum));
 	}
 	/*
 	 * In replace mode:

src/testdir/test_mapping.vim

@@ -160,3 +160,14 @@ func Test_map_meta_quotes()
   set nomodified
   iunmap <M-">
 endfunc
+
+func Test_abbr_after_line_join()
+  new
+  abbr foo bar
+  set backspace=indent,eol,start
+  exe "normal o\<BS>foo "
+  call assert_equal("bar ", getline(1))
+  bwipe!
+  unabbr foo
+  set backspace&
+endfunc

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    533,
 /**/
     532,
 /**/