patch 8.1.2238: error in docs tags goes unnoticed

Problem:    Error in docs tags goes unnoticed.
Solution:   Adjust tags build command. (Ken Takata, closes #5158)
diff --git a/.travis.yml b/.travis.yml
index 4625bcf..f96564b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -142,7 +142,10 @@
       "${SRCDIR}"/vim --not-a-term -u NONE -S "${SRCDIR}"/testdir/if_ver-2.vim -c quit > /dev/null
       cat if_ver.txt
     fi
-  - do_test make ${SHADOWOPT} ${TEST} && FOLD_MARKER=travis_fold
+  - >
+    do_test make ${SHADOWOPT} ${TEST} &&
+    make -C runtime/doc vimtags VIMEXE=../../"${SRCDIR}"/vim &&
+    FOLD_MARKER=travis_fold
   - echo -en "${FOLD_MARKER}:end:test\\r\\033[0K"
 
 
diff --git a/Filelist b/Filelist
index a2b9f0a..6cb5f63 100644
--- a/Filelist
+++ b/Filelist
@@ -663,6 +663,7 @@
 		runtime/doc/*.txt \
 		runtime/doc/Makefile \
 		runtime/doc/doctags.c \
+		runtime/doc/doctags.vim \
 		runtime/doc/test_urls.vim \
 		runtime/doc/vim.1 \
 		runtime/doc/evim.1 \
diff --git a/runtime/doc/Makefile b/runtime/doc/Makefile
index 4a1ea03..443a27a 100644
--- a/runtime/doc/Makefile
+++ b/runtime/doc/Makefile
@@ -323,7 +323,7 @@
 # Use Vim to generate the tags file.  Can only be used when Vim has been
 # compiled and installed.  Supports multiple languages.
 vimtags: $(DOCS)
-	$(VIMEXE) -u NONE -esX -c "helptags ++t ." -c quit
+	$(VIMEXE) -eX -u doctags.vim
 
 # Use "doctags" to generate the tags file.  Only works for English!
 tags: doctags $(DOCS)
diff --git a/runtime/doc/doctags.vim b/runtime/doc/doctags.vim
new file mode 100644
index 0000000..7dfbcc0
--- /dev/null
+++ b/runtime/doc/doctags.vim
@@ -0,0 +1,6 @@
+" This script makes a tags file for help text.
+"
+" Usage: vim -eX -u doctags.vim
+
+helptags ++t .
+qa!
diff --git a/src/version.c b/src/version.c
index 3eaf21f..e1d5c64 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2238,
+/**/
     2237,
 /**/
     2236,