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+### Please describe the problem.
+
+git-annex uses a custom setup script but does not have a custom-setup stanza. This causes
+git-annex to be unbuildable with `cabal new-build` and I'm told it's also unbuildable with
+the old `cabal build` under certain circumstances.
+
+### What steps will reproduce the problem?
+
+Try building git-annex with `cabal new-build`.
+
+### What version of git-annex are you using? On what operating system?
+
+git-annex-6.20171214 on Debian GNU/Linux 9.
+
+### Please provide any additional information below.
+
+[[!format sh """
+# If you can, paste a complete transcript of the problem occurring here.
+# If the problem is with the git-annex assistant, paste in .git/annex/daemon.log
+
+$ cabal new-build --constraint="any.git-annex -testsuite" 
+Resolving dependencies...
+In order, the following will be built (use -v for more details):
+ - git-annex-6.20171214 (exe:git-annex) -testsuite -dbus -concurrentoutput (requires build)
+ - dummypkg-0 (lib) (first run)
+Configuring git-annex-6.20171214 (all, legacy fallback)...
+cabal: Failed to build git-annex-6.20171214 (which is required by dummypkg-0).
+The failure occurred during the configure step. The exception was:
+dieVerbatim: user error (cabal: '/usr/bin/ghc' exited with an error:
+
+/home/matthew/dummypkg/dist-newstyle/tmp/src-3285/git-annex-6.20171214/Utility/FileSize.hs:10:1:
+error:
+Failed to load interface for ‘System.PosixCompat.Files’
+It is a member of the hidden package ‘unix-compat-0.5.0.1’.
+Perhaps you need to add ‘unix-compat’ to the build-depends in your .cabal
+file.
+Use -v to see a list of the files searched for.
+)
+
+# End of transcript or log.
+"""]]
+
+### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)
+
+Yeah, it's amazing! I've been using the version from the Debian repos and then
+wanted to try building the new version for youtube-dl support.