vim-patch:8.1.1546: in some tests 'tags' is set but not restored

Problem:    In some tests 'tags' is set but not restored. (Daniel Hahler)
Solution:   Restore 'tags'. (closes vim/vim#4535)
0331faf712

src/nvim/testdir/test_autocmd.vim

@@ -635,7 +635,8 @@ func Test_OptionSet()
 
   " Cleanup
   au! OptionSet
-  for opt in ['nu', 'ai', 'acd', 'ar', 'bs', 'backup', 'cul', 'cp']
+  " set tags&
+  for opt in ['nu', 'ai', 'acd', 'ar', 'bs', 'backup', 'cul', 'cp', 'tags']
     exe printf(":set %s&vim", opt)
   endfor
   call test_override('starting', 0)

src/nvim/testdir/test_cmdline.vim

@@ -294,6 +294,7 @@ func Test_getcompletion()
   endfor
 
   call delete('Xtags')
+  set tags&
 
   call assert_fails('call getcompletion("", "burp")', 'E475:')
 endfunc

src/nvim/testdir/test_options.vim

@@ -225,6 +225,7 @@ func Test_set_completion()
 
   call feedkeys(":set tags=./\\\\ dif\<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"set tags=./\\ diff diffexpr diffopt', @:)
+  set tags&
   let &shellslash = shellslash
 endfunc
 

src/nvim/testdir/test_tagcase.vim

@@ -44,6 +44,7 @@ func Test_tagcase()
   endfor
 
   call delete('Xtags')
+  set tags&
   set ic&
   setg tc&
   setl tc&

src/nvim/testdir/test_tagjump.vim

@@ -20,6 +20,7 @@ func Test_cancel_ptjump()
   call assert_equal(2, winnr('$'))
 
   call delete('Xtags')
+  set tags&
   quit
 endfunc
 
@@ -104,6 +105,7 @@ func Test_tagjump_switchbuf()
   enew | only
   call delete('Xfile1')
   call delete('Xtags')
+  set tags&
   set switchbuf&vim
 endfunc
 
@@ -424,7 +426,7 @@ func Test_tagnr_recall()
   tag
   call assert_equal(bufname('%'), 'Xtest.h')
 
-  set tag&
+  set tags&
   call delete('Xtags')
   bwipe Xtest.h
   bwipe Xtest.c
@@ -460,6 +462,7 @@ func Test_tag_line_toolong()
   endtry
   call assert_equal('Ignoring long line in tags file', split(execute('messages'), '\n')[-1])
   call delete('Xtags')
+  set tags&
   let &verbose = old_vbs
 endfunc
 

src/nvim/testdir/test_taglist.vim

@@ -16,6 +16,7 @@ func Test_taglist()
   call assert_equal(['BFoo', 'FFoo'], map(taglist("Foo", "Xbar"), {i, v -> v.name}))
 
   call delete('Xtags')
+  set tags&
   bwipe
 endfunc
 
@@ -36,6 +37,7 @@ func Test_taglist_native_etags()
 	\ map(taglist('set_signals'), {i, v -> [v.name, v.cmd]}))
 
   call delete('Xtags')
+  set tags&
 endfunc
 
 func Test_taglist_ctags_etags()
@@ -55,6 +57,7 @@ func Test_taglist_ctags_etags()
 	\ map(taglist('set_signals'), {i, v -> [v.name, v.cmd]}))
 
   call delete('Xtags')
+  set tags&
 endfunc
 
 func Test_tags_too_long()
@@ -73,6 +76,7 @@ func Test_tagsfile_without_trailing_newline()
   call assert_equal('Foo', tl[0].name)
 
   call delete('Xtags')
+  set tags&
 endfunc
 
 func Test_tagfiles()