Simplify project regex further

Summary: Fixes T16028

Test Plan:
Assert that `#js-draw-lib` (or any other project name with one or two characters followed by a non-word) links correctly. It was previously parsed as `#js -draw-lib`.

Repeat the test plan for D25838 and observe it still works

Reviewers: aklapper, O1 Blessed Committers, bekay, valerio.bozzolan

Reviewed By: O1 Blessed Committers, bekay, valerio.bozzolan

Subscribers: mainframe98, bekay, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T16028

Differential Revision: https://we.phorge.it/D25959

src/applications/project/remarkup/ProjectRemarkupRule.php

@@ -40,12 +40,7 @@ final class ProjectRemarkupRule extends PhabricatorObjectRemarkupRule {
     $never_edge = '.';
 
     return '(?:'.
-        // Short project name with one or two characters not in $never_edge or
-        '[^'.$never_edge.$never.']{1,2}|'.
-        // A single character not in $never or $never_edge,
-        // then any number of characters not in $never then a single character
-        // not in $never or $never_edge
-        '[^'.$never_edge.$never.'][^'.$never.']+[^'.$never_edge.$never.']'.
+        '[^'.$never_edge.$never.'](?:[^'.$never.']*[^'.$never_edge.$never.'])?'.
     ')';
   }
 

src/applications/project/remarkup/__tests__/ProjectRemarkupRuleTestCase.php

@@ -135,6 +135,21 @@ final class ProjectRemarkupRuleTestCase extends PhabricatorTestCase {
         ),
       ),
 
+      // This test case failed in an old version of the regex
+      '#js-draw' => array(
+        'embed' => array(),
+        'ref' => array(
+          array(
+            'offset' => 1,
+            'id' => 'js-draw',
+          ),
+        ),
+     ),
+     // Don't match leading dots for consistency with trailing ones
+     '#.js' => array(
+        'embed' => array(),
+        'ref' => array(),
+     ),
     );
 
     foreach ($cases as $input => $expect) {