Unregister thread even if is the last one

Mihails Strasuns · Mihails Strasuns · commit f0abd064f46f · 2018-10-24T10:23:20.000+01:00
Previously `remove` implementation would early return if removed thread
is the only element in the registered list (and thus has no prev/next
references)
diff --git a/src/core/thread.d b/src/core/thread.d
@@ -1859,8 +1859,9 @@ private:
     do
     {
         // Thread was already removed earlier, might happen b/c of thread_detachInstance
-        if (!t.next && !t.prev)
+        if (!t.next && !t.prev && (sm_tbeg !is t))
             return;
+
         slock.lock_nothrow();
         {
             // NOTE: When a thread is removed from the global thread list its

Original file line number	Diff line number	Diff line change
`@@ -1859,8 +1859,9 @@ private:`
`1859`	`1859`	`do`
`1860`	`1860`	`{`
`1861`	`1861`	`// Thread was already removed earlier, might happen b/c of thread_detachInstance`
`1862`		`- if (!t.next && !t.prev)`
	`1862`	`+ if (!t.next && !t.prev && (sm_tbeg !is t))`
`1863`	`1863`	`return;`
	`1864`	`+`
`1864`	`1865`	`slock.lock_nothrow();`
`1865`	`1866`	`{`
`1866`	`1867`	`// NOTE: When a thread is removed from the global thread list its`