vim-patch:8.0.0184: fix ex-mode exit code #7943

Problem:    When in Ex mode and an error is caught by try-catch, Vim still
            exits with a non-zero exit code.
Solution:   Don't set ex_exitval when inside a try-catch. (partly by Christian
            Brabandt)

2b7bc567b9

src/nvim/message.c

@@ -487,9 +487,6 @@ int emsg(const char_u *s_)
   }
 
   called_emsg = true;
-  if (emsg_silent == 0) {
-    ex_exitval = 1;
-  }
 
   // If "emsg_severe" is TRUE: When an error exception is to be thrown,
   // prefer this message over previous messages for the same command.
@@ -540,6 +537,8 @@ int emsg(const char_u *s_)
       return true;
     }
 
+    ex_exitval = 1;
+
     // Reset msg_silent, an error causes messages to be switched back on.
     msg_silent = 0;
     cmd_silent = FALSE;

src/nvim/testdir/test_system.vim

@@ -46,3 +46,40 @@ function! Test_System()
 
   call assert_fails('call system("wc -l", 99999)', 'E86:')
 endfunction
+
+function! Test_system_exmode()
+  let cmd=" -es --headless -u NONE -c 'source Xscript' +q; echo $?"
+  " Need to put this in a script, "catch" isn't found after an unknown
+  " function.
+  call writefile(['try', 'call doesnotexist()', 'catch', 'endtry'], 'Xscript')
+  let a = system(v:progpath . cmd)
+  call assert_equal('0', a[0])
+  call assert_equal(0, v:shell_error)
+
+  " Error before try does set error flag.
+  call writefile(['call nosuchfunction()', 'try', 'call doesnotexist()', 'catch', 'endtry'], 'Xscript')
+  let a = system(v:progpath . cmd)
+  call assert_notequal('0', a[0])
+
+  let cmd=" -es --headless -u NONE -c 'source Xscript' +q"
+  let a = system(v:progpath . cmd)
+  call assert_notequal(0, v:shell_error)
+
+  let cmd=" -es --headless -u NONE -c 'call doesnotexist()' +q; echo $?"
+  let a = system(v:progpath. cmd)
+  call assert_notequal(0, a[0])
+
+  let cmd=" -es --headless -u NONE -c 'call doesnotexist()' +q"
+  let a = system(v:progpath. cmd)
+  call assert_notequal(0, v:shell_error)
+
+  let cmd=" -es --headless -u NONE -c 'call doesnotexist()|let a=1' +q; echo $?"
+  let a = system(v:progpath. cmd)
+  call assert_notequal(0, a[0])
+
+  let cmd=" -es --headless -u NONE -c 'call doesnotexist()|let a=1' +q"
+  let a = system(v:progpath. cmd)
+  call assert_notequal(0, v:shell_error)
+
+  call delete('Xscript')
+endfunc