why does ivy:install populate the cache?

[Jeffrey Blattman]

this was unexpected. i was exploring ways to modify the code to be able 
to set a default value for /useOrigin/, and found out that my use of 
/ivy:install/ was populating it anyway.

i can see where it might do this as a shortcut w/ the expectation that 
if it's installed into a repo then it's going to be accessed, but it 
doesn't seem to fit with the definition of install ... ?

or am i missing something?

thanks.