anti-tarball clause and GPL

[Adam Borowski <kilobyte@angband.pl>]

Hi!
In the light of the currently discussed GR proposal, I wonder if the
following license clause would be considered DFSG-free and GPL-compatible:

##################
I do not consider a flat tarball to be a preferred form for modification. 
Thus, like any non-source form, it must be accompanied by a way to obtain
the actual form for modification.  There are many such ways -- unless you
distribute the software in highly unusual circumstances, a link to a
network server suffices; see the text of the GPL for further details.
##################

I believe such a statement would be GPL-compatible; rationale:
* by the 2011 Red Hat kernel sources outcry, it is obvious such a tarball
  is long obsolete
* a flat tarball deprives the recipient of features of modern VCSes
* comments giving rationale for a change tend to be written as VCS commit
  messages
* future forms are not banned: it is conceivable that next week someone
  invents a revolutionary new form that wins over git

Thoughts?


Meow!
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