3 files changed, 34 insertions, 2 deletions
diff --git a/lib/stdlib/doc/src/supervisor.xml b/lib/stdlib/doc/src/supervisor.xml
index 6d5065ca02..0e8075a578 100644
--- a/lib/stdlib/doc/src/supervisor.xml
+++ b/lib/stdlib/doc/src/supervisor.xml
@@ -208,8 +208,16 @@ child_spec() = #{id => child_id(),       % mandatory
           the child process is unconditionally terminated using
           <c>exit(Child,kill)</c>.</p>
         <p>If the child process is another supervisor, the shutdown time
-          is to be set to <c>infinity</c> to give the subtree ample
-          time to shut down. It is also allowed to set it to <c>infinity</c>,
+          must be set to <c>infinity</c> to give the subtree ample
+          time to shut down.</p>
+	<warning>
+	  <p>Setting the shutdown time to anything other
+	    than <c>infinity</c> for a child of type <c>supervisor</c>
+	    can cause a race condition where the child in question
+	    unlinks its own children, but fails to terminate them
+	    before it is killed.</p>
+	</warning>
+	<p>It is also allowed to set it to <c>infinity</c>,
           if the child process is a worker.</p>
         <warning>
           <p>Be careful when setting the shutdown time to
diff --git a/lib/stdlib/test/re_SUITE_data/testoutput2 b/lib/stdlib/test/re_SUITE_data/testoutput2
index 811bbefc84..61ed8d9d4e 100644
--- a/lib/stdlib/test/re_SUITE_data/testoutput2
+++ b/lib/stdlib/test/re_SUITE_data/testoutput2
@@ -14705,4 +14705,20 @@ No options
 No first char
 No need char
 
+"(?<=(a))\1?b"
+    ab
+ 0: b
+ 1: a
+    aaab 
+ 0: ab
+ 1: a
+
+"(?=(a))\1?b"
+    ab
+ 0: ab
+ 1: a
+    aaab 
+ 0: ab
+ 1: a
+
 /-- End of testinput2 --/
diff --git a/lib/stdlib/test/re_SUITE_data/testoutput5 b/lib/stdlib/test/re_SUITE_data/testoutput5
index bab989ca7e..090e1e1c85 100644
--- a/lib/stdlib/test/re_SUITE_data/testoutput5
+++ b/lib/stdlib/test/re_SUITE_data/testoutput5
@@ -1942,4 +1942,12 @@ Need char = 'z'
  0: \x{17f}
  0+ 
 
+/\C[^\v]+\x80/8
+    [AΏBŀC]
+No match
+
+/\C[^\d]+\x80/8
+    [AΏBŀC]
+No match
+
 /-- End of testinput5 --/