How do I prevent (or detect) package.el from reloading my package's files?

[Clément Pit-Claudel]

Hi all,

We've finally packaged proof-general for package.el.  But we're running in a 
thorny issue.

The usual package.el installation process goes like this:

* Unpack proof-general.xyz.tar
* Reload any proof-general files found in load-history
* Compile all unpacked files (this adds a bunch of things to load-history)
* Reload any proof-general files found in load-history (this reloads all the 
files that were `require'd during compilation)

This last step is giving us a lot of trouble.  For historical reasons, files in 
proof-general can't be loaded unconditionally; they contain macros that require 
certain variables to be defined. They can be compiled, though, because of code 
like this:

(unless (bound-and-true-p byte-compile-current-file)
   (proof-add-completions))

Is there a similar trick to detect that we're being reloaded by package.el?  
Alternatively, is there a way to skip this reloading step?

Thanks!
Clément.