Based on darcs.cabal, the Network library should only be necessary if
I'm not using curl.  But ./configure fails if it can't find Network.

$ pkg-config --modversion libcurl
7.18.2
$ ghc-pkg list network
/usr/lib/ghc-6.10.1/./package.conf:
$ ./configure
checking for darcs... darcs
checking if we're in a darcs repository... yes
checking for a BSD-compatible install... /usr/bin/install -c
checking for gcc... gcc
checking for C compiler default output file name... a.out
checking whether the C compiler works... yes
checking whether we are cross compiling... no
checking for suffix of executables...
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
checking how to run the C preprocessor... gcc -E
checking for grep that handles long lines and -e... /bin/grep
checking for egrep... /bin/grep -E
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking windows.h usability... no
checking windows.h presence... no
checking for windows.h... no
checking for ghc... ghc
found The Glorious Glasgow Haskell Compilation System, version 6.10.1
checking for ghc-pkg... ghc-pkg
checking base package... base-3.0.3.0
checking whether to profile... no
checking whether to use the threaded runtime... yes
checking siginfo.h usability... no
checking siginfo.h presence... no
checking for siginfo.h... no
checking for module Text.Regex( mkRegex, matchRegex, Regex )... no; and neither in package text
checking for module Text.Regex( mkRegex, matchRegex, Regex )... in package regex-compat
checking for module Network.URI... no; and neither in package network
configure: error: Cannot find Network.URI; try installing the package network?
$

It sounds like this is safe to leave to benign neglect (since we're ditching
autoconf after July).  It's not actually hurting anybody (unless I
misunderstand), just forcing them to unnecessarily install stuff.