python-smartpm should not conflict with the old smartpm-core package

<niemeyer> cjwatson: I think we found the issue
<niemeyer> cjwatson: The new python-smartpm package has a Conflicts relation with the old smartpm-core package
<cjwatson> ah, heh, that's a bug in the package
<cjwatson> I actually thought about mentioning that when I saw it in NEW
<cjwatson> silly me for not doing so
<cjwatson> Replaces is quite sufficient
<niemeyer> cjwatson: Doesn't that mean that both might be installed at the same time?
<niemeyer> cjwatson: Should we use Breaks perhaps?
<cjwatson> Replaces is good enough.
<cjwatson> it's just a file move
<niemeyer> cjwatson: Ok, cool

The change which introduced the Pre-Depends on smartpm-core -> python-smartpm was incorrect; it should be reverted, and instead the conflict should be removed.

Here's the rationale for reverting the last change:

<radix> cjwatson: ok, so smartpm-core installs a symlink /usr/bin/smart -> /usr/share/smart/smart; python-smartpm installs /usr/share/smart/smart
<radix> cjwatson: smartpm-core invokes 'smart' in its own postinst
<cjwatson> hunger: -fno-stack-protector
<cjwatson> radix: that only requires Depends
<radix> cjwatson: does a Depend guarantee that the depended-upon package will be unpacked before the depending package?
<cjwatson> radix: you would only need Pre-Depends if you were invoking smart in smartpm-core's preinst
<cjwatson> radix: yes, absolutely!
<radix> humm, we actually found an error
<cjwatson> Pre-Depends is usually not the right fix, and policy explicitly says that you must discuss new Pre-Depends
<cjwatson> precisely because they're usually the wrong fix and complicate upgrades
<radix> ah. woops. :-(