vim-patch:7.4.1282

Problem:    Crash when evaluating the pattern of ":catch" causes an error.
            (Dominique Pelle)
Solution:   Block error messages at this point.

768ce2435a

Applied manually. Could not reproduce the crash both using vim and nvim,
therefore could not device a test.

Should be merged anyways, since it's in vim?

src/nvim/ex_eval.c

@@ -1370,7 +1370,11 @@ void ex_catch(exarg_T *eap)
         }
         save_cpo  = p_cpo;
         p_cpo = (char_u *)"";
+        // Disable error messages, it will make current exception
+        // invalid
+        ++emsg_off;
         regmatch.regprog = vim_regcomp(pat, RE_MAGIC + RE_STRING);
+        --emsg_off;
         regmatch.rm_ic = FALSE;
         if (end != NULL)
           *end = save_char;