patch 8.1.1346: error for Python exception does not show useful info

Problem:    Error for Python exception does not show useful info.
Solution:   Show the last line instead of the first one. (Ben Jackson,
            closes #4381)

src/if_py_both.h

@@ -412,6 +412,8 @@ write_output(OutputObject *self, PyObject *string)
 
     Py_BEGIN_ALLOW_THREADS
     Python_Lock_Vim();
+    if (error)
+	emsg_severe = TRUE;
     writer((writefn)(error ? emsg : msg), (char_u *)str, len);
     Python_Release_Vim();
     Py_END_ALLOW_THREADS

src/testdir/test86.ok

@@ -91,7 +91,7 @@ pyeval("None") = v:none
 0.0
 "\0":	Vim(let):E859:
 {"\0": 1}:	Vim(let):E859:
-undefined_name:	Vim(let):Trace
+undefined_name:	Vim(let):NameE
 vim:	Vim(let):E859:
 [1]
 [1, 10, 11, 10, 11, 10, 11, 10, 11, 10, 11, 10, 1]

src/testdir/test87.ok

@@ -91,7 +91,7 @@ py3eval("None") = v:none
 0.0
 "\0":	Vim(let):E859:
 {"\0": 1}:	Vim(let):E859:
-undefined_name:	Vim(let):Trace
+undefined_name:	Vim(let):NameE
 vim:	Vim(let):E859:
 [1]
 [1, 10, 11, 10, 11, 10, 11, 10, 11, 10, 11, 10, 1]

src/testdir/test_python2.vim

@@ -160,3 +160,11 @@ func Test_Write_To_Current_Buffer_Fixes_Cursor_Str()
 
   bwipe!
 endfunction
+
+func Test_Catch_Exception_Message()
+  try
+    py raise RuntimeError( 'TEST' )
+  catch /.*/
+    call assert_match( '^Vim(.*):RuntimeError: TEST$', v:exception )
+  endtry
+endfunc

src/testdir/test_python3.vim

@@ -160,3 +160,11 @@ func Test_Write_To_Current_Buffer_Fixes_Cursor_Str()
 
   bwipe!
 endfunction
+
+func Test_Catch_Exception_Message()
+  try
+    py3 raise RuntimeError( 'TEST' )
+  catch /.*/
+    call assert_match( '^Vim(.*):RuntimeError: TEST$', v:exception )
+  endtry
+endfunc

src/testdir/test_pyx2.vim

@@ -72,3 +72,11 @@ func Test_pyxfile()
     call assert_match(s:py3pattern, split(var)[0])
   endif
 endfunc
+
+func Test_Catch_Exception_Message()
+  try
+    pyx raise RuntimeError( 'TEST' )
+  catch /.*/
+    call assert_match( '^Vim(.*):RuntimeError: TEST$', v:exception )
+  endtry
+endfunc

src/testdir/test_pyx3.vim

@@ -72,3 +72,11 @@ func Test_pyxfile()
     call assert_match(s:py2pattern, split(var)[0])
   endif
 endfunc
+
+func Test_Catch_Exception_Message()
+  try
+    pyx raise RuntimeError( 'TEST' )
+  catch /.*/
+    call assert_match( '^Vim(.*):RuntimeError: TEST$', v:exception )
+  endtry
+endfunc

src/version.c

@@ -767,6 +767,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1346,
 /**/
     1345,
 /**/