Bug 367539 - When upgrading an existing install use the uninstall.log to uninstall the previous version before install. Add insertmacro GetSingleInstallPath in Thunderbird's installer.nsi. r=philringnalda

mail/installer/windows/nsis/installer.nsi

@@ -111,6 +111,7 @@ VIAddVersionKey "OriginalFilename" "setup.exe"
 !insertmacro FindSMProgramsDir
 !insertmacro GetPathFromString
 !insertmacro GetParent
+!insertmacro GetSingleInstallPath
 !insertmacro IsHandlerForInstallDir
 !insertmacro ManualCloseAppPrompt
 !insertmacro RegCleanMain