Merge branch 'dgud/patch-26/kvakvs/nsis-deleteregkey-api-change/OTP-19683' into maint-27

* dgud/patch-26/kvakvs/nsis-deleteregkey-api-change/OTP-19683:
  Add extra uninstall removal instructions, thanks to @inikulshin
  Bugfix: API change in NSIS scripting as of 3.0.6 (July 2020) in DeleteRegKey use /ifnosubkeys for old behaviour

Author: Erlang/OTP

erts/etc/win32/nsis/erlang20.nsi

@@ -482,12 +482,16 @@ continue_delete:
 
 noshortcuts:
 ; We delete both in HKCU and HKLM, we don't really know were they might be...
-  	DeleteRegKey /ifempty HKLM "SOFTWARE\Ericsson\Erlang\${ERTS_VERSION}"
-  	DeleteRegKey /ifempty HKCU "SOFTWARE\Ericsson\Erlang\${ERTS_VERSION}"
-  	DeleteRegKey HKLM \
-		"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Erlang OTP"
-  	DeleteRegKey HKCU \
-		"SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Erlang OTP"
+	DeleteRegKey /ifnosubkeys HKCU "SOFTWARE\Ericsson\Erlang\${ERTS_VERSION}"
+	DeleteRegKey /ifnosubkeys HKCU "SOFTWARE\Ericsson\Erlang"
+	DeleteRegKey /ifnosubkeys HKCU "SOFTWARE\Ericsson"
+
+	DeleteRegKey /ifnosubkeys HKLM "SOFTWARE\Ericsson\Erlang\${ERTS_VERSION}"
+	DeleteRegKey /ifnosubkeys HKLM "SOFTWARE\Ericsson\Erlang"
+	DeleteRegKey /ifnosubkeys HKLM "SOFTWARE\Ericsson"
+
+	DeleteRegKey HKLM "SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Erlang OTP"
+	DeleteRegKey HKCU "SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Erlang OTP"
 
 
 ; Now remove shell/file associations we'we made...