Help with ensuring a bootstrapper is used but having upgrades work

We have an MSI we have authored in WiX 3.5.2030.0 and targeting Windows Installer 4.0 (for MSIUSEREALADMINDETECTION support). We have a property that we have defined in the MSI to enforce use of a bootstrapper (I say "enforce" but it's really "very strongly encourage" of course):

<Property Id="SETUPEXE"
          Secure="yes" />
<Condition Message="You must run the MSI through the setup program; you cannot run it directly.">
  SETUPEXE = 1
</Condition>

When we run the produced MSI as a new install, everything works. When we run it as an upgrade, however, the property pass开发者_开发百科ed in to the installer seems to be "lost" at some point. The log shows the following relevant entries:

MSI (s) (2C:8C) [11:27:41:648]: Command Line: SETUPEXE=1 <other properties>

MSI (s) (2C:8C) [11:27:43:055]: PROPERTY CHANGE: Adding SETUPEXE property. Its value is '1'.

MSI (s) (2C:CC) [11:28:11:038]: PROPERTY CHANGE: Adding NETFRAMEWORK20INSTALLROOTDIR property. Its value is 'C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\'.
Action ended 11:28:11: AppSearch. Return value 1.
MSI (s) (2C:CC) [11:28:11:147]: Doing action: LaunchConditions
Action start 11:28:11: LaunchConditions.
MSI (s) (2C:CC) [11:28:33:662]: Product: <product> -- You must run the MSI through the setup program; you cannot run it directly.

Action ended 11:28:33: LaunchConditions. Return value 3.
Action ended 11:28:33: INSTALL. Return value 3.

Property(N): SETUPEXE = 0

Property(N): SecureCustomProperties = NETFRAMEWORK20INSTALLROOTDIR;NETFRAMEWORK35;NETFRAMEWORK35_SP_LEVEL;NEWERVERSIONDETECTED;OLDERVERSIONBEINGUPGRADED;SETUPEXE

Property(S): SecureCustomProperties = NETFRAMEWORK20INSTALLROOTDIR;NETFRAMEWORK35;NETFRAMEWORK35_SP_LEVEL;NEWERVERSIONDETECTED;OLDERVERSIONBEINGUPGRADED;SETUPEXE

Property(S): SETUPEXE = 1

I have done some searching on this and looked at the log in WiLogUtl and have at least figured out that Property(N) indicates a "nested" property, but I don't know what the nesting is when I'm running the MSI directly through msiexec. Then, I don't know why the nested property is not set correctly when the client and server values are correct. How do I resolve this?

I'd consider changing that condition to ( or similar depending on your use case )

<Condition Message="Blah blah blah">SETUPEXE or Installed</Condition> 

I do a similar thing ( InstallShield setup.exe passes a SETUPEXEDIR property by default ) and it's not a horrible thing to do if you want to make sure your installer was run through the bootstrapper to ensure prereqs had a chance to be installed. But for maintenance / repair / uninstall scenarios you probably don't want to require the setup.exe to be run.