patch 8.1.1061: when substitute string throws error, substitute happens anyway

Problem:    When substitute string throws error, substitute happens anyway.
Solution:   Skip substitution when aborting. (closes #4161)

src/ex_cmds.c

@@ -5574,7 +5574,12 @@ do_sub(exarg_T *eap)
 				    sub_firstlnum - regmatch.startpos[0].lnum,
 				    sub, sub_firstline, FALSE, p_magic, TRUE);
 #ifdef FEAT_EVAL
-		/* Don't keep flags set by a recursive call. */
+		// If getting the substitute string caused an error, don't do
+		// the replacement.
+		if (aborting())
+		    goto skip;
+
+		// Don't keep flags set by a recursive call.
 		subflags = subflags_save;
 		if (subflags.do_count)
 		{

src/testdir/test_substitute.vim

@@ -610,3 +610,33 @@ func Test_sub_cmd_8()
   enew!
   set titlestring&
 endfunc
+
+func Test_nocatch_sub_failure_handling()
+  " normal error results in all replacements 
+  func! Foo()
+    foobar
+  endfunc
+  new
+  call setline(1, ['1 aaa', '2 aaa', '3 aaa'])
+  %s/aaa/\=Foo()/g
+  call assert_equal(['1 0', '2 0', '3 0'], getline(1, 3))
+
+  " Trow without try-catch causes abort after the first line.
+  " We cannot test this, since it would stop executing the test script.
+
+  " try/catch does not result in any changes
+  func! Foo()
+    throw 'error'
+  endfunc
+  call setline(1, ['1 aaa', '2 aaa', '3 aaa'])
+  let error_caught = 0
+  try
+    %s/aaa/\=Foo()/g
+  catch
+    let error_caught = 1
+  endtry
+  call assert_equal(1, error_caught)
+  call assert_equal(['1 aaa', '2 aaa', '3 aaa'], getline(1, 3))
+
+  bwipe!
+endfunc

src/version.c

@@ -775,6 +775,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1061,
 /**/
     1060,
 /**/