Prevent false-positive ref syntax highlighting in Gstatus

Subject lines that begin with an open parenthesis and have no other refs
attached have their first parenthesised text syntax highlighted.

Use concealed artificial parentheses in such cases.

Author: Gelio

autoload/fugitive.vim

@@ -1705,33 +1705,49 @@ function! s:IgnoreRefs(refs, refsToIgnore) abort
     return index(a:refsToIgnore, a:ref) == -1
   endfunction
 
+  " Strip the outer parentheses
   let refs = split(a:refs[1:-2], ", ")
   let refs = filter(refs, function('ShouldPreserveRef', [a:refsToIgnore]))
 
   if len(a:refs) == 0
     return ''
   endif
 
-  return '(' . join(refs, ", ") . ')'
+  return '(' . join(refs, ", ") . ') '
 endfunction
 
 function! s:QueryLog(refspec, refToIgnore) abort
   let lines = s:LinesError(['log', '-n', '256', '--pretty=format:%h%x09%d%x09%s', a:refspec, '--'])[0]
   call map(lines, 'split(v:val, "\t", 1)')
   let refsToIgnore = [a:refToIgnore, 'HEAD']
 
-  function! HandleRefs(refsToIgnore, refs) abort
-    return s:IgnoreRefs(trim(a:refs), a:refsToIgnore)
+  function! HandleRefs(refsToIgnore, subject, refs) abort
+    let refs = trim(a:refs)
+    let refs = s:IgnoreRefs(refs, a:refsToIgnore)
+
+    if len(refs) == 0 && a:subject[0] == '('
+      " Add artificial (concealed) empty parentheses for refs. Helps avoid
+      " syntax highlighting false-positives (subject lines beginning with an
+      " open parenthesis).
+      return '()'
+    endif
+
+    return refs
+  endfunction
+  
+  function! CreateLineDict(refsToIgnore, index, parts) abort
+    let subject = join(a:parts[2 : -1], "\t")
+    return {"type": "Log", "commit": a:parts[0], "refs": HandleRefs(a:refsToIgnore, subject, a:parts[1]), "subject": subject}
   endfunction
 
-  call map(lines, '{"type": "Log", "commit": v:val[0], "refs": ' . string(function('HandleRefs', [refsToIgnore])) . '(v:val[1]), "subject": join(v:val[2 : -1], "\t")}')
+  call map(lines, function('CreateLineDict', [refsToIgnore]))
   return lines
 endfunction
 
 function! s:FormatLog(dict) abort
   setlocal conceallevel=3
   setlocal concealcursor=nc
-  return a:dict.commit . ' ' . ((len(a:dict.refs) > 0) ? ("\x1f" . a:dict.refs . ' ') : '') . a:dict.subject
+  return a:dict.commit . ' ' . ((len(a:dict.refs) > 0) ? a:dict.refs : '') . a:dict.subject
 endfunction
 
 function! s:FormatRebase(dict) abort

syntax/fugitive.vim

@@ -23,9 +23,9 @@ syn match fugitiveDone /^done\>/ contained containedin=@fugitiveSection nextgrou
 syn match fugitiveStop /^stop\>/ contained containedin=@fugitiveSection nextgroup=fugitiveHash skipwhite
 syn match fugitiveModifier /^[MADRCU?]\{1,2} / contained containedin=@fugitiveSection
 syn match fugitiveSymbolicRef /\.\@!\%(\.\.\@!\|[^[:space:][:cntrl:]\:.]\)\+\.\@<!/ contained
-syn match fugitiveHash /^\x\{4,\}\S\@!/ contained containedin=@fugitiveSection nextgroup=fugitiveRefsConcealedMarker skipwhite
+syn match fugitiveHash /^\x\{4,\}\S\@!/ contained containedin=@fugitiveSection nextgroup=fugitiveRefs skipwhite
 syn match fugitiveHash /\S\@<!\x\{4,\}\S\@!/ contained
-syn match fugitiveRefsConcealedMarker "\%x1f" contained nextgroup=fugitiveRefs conceal
+syn match fugitiveRefs '()' contained conceal
 syn match fugitiveRefs /([^)]\+)/hs=s+1,he=e-1 contained
 
 syn region fugitiveHunk start=/^\%(@@\+ -\)\@=/ end=/^\%([A-Za-z?@]\|$\)\@=/ contains=@fugitiveDiff containedin=@fugitiveSection fold