Instead of relying on $$ to not collide with an existing path.
Quoting the Bash manual about $$:
> Expands to the process ID of the shell. In a () subshell, it expands
> to the process ID of the current shell, not the subshell.
So, this is different from $BASHPID:
> Expands to the process ID of the current bash process. This differs
> from $$ under certain circumstances, such as subshells that do not
> require bash to be re-initialized.
But even $BASHPID is prone to race conditions if the process IDs wrap
around, so to be on the safe side, we're using mktemp here.
Closes#3784.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
the tree being fetched from a Subversion repository. The revision
number is now optional (and defaults to HEAD).
This makes `fetchsvn' more pure. First, a URL/revision tuple does
not uniquely identify a file resource, since the repository itself
might change. Second, `svn:external' attributes can cause arbitrary
resources to be exported.
A script `nix-prefetch-svn' has been provided to determine the hash
of a URL.
svn path=/nixpkgs/trunk/; revision=938
