Add a work-around for some Debian porterboxes

debian/patches/d-host-duplicates.patch

@@ -0,0 +1,29 @@
+Description: Work around #842634 on some machines, e.g. Debian porterboxes
+ This should remain commented-out in debian/patches/series, it's not needed everywhere
+Author: Ximin Luo <infinity0@debian.org>
+Forwarded: not-needed
+---
+This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
+--- a/src/libstd/sys_common/net.rs
++++ b/src/libstd/sys_common/net.rs
+@@ -616,20 +616,3 @@
+             .finish()
+     }
+ }
+-
+-#[cfg(test)]
+-mod tests {
+-    use super::*;
+-    use collections::HashMap;
+-
+-    #[test]
+-    fn no_lookup_host_duplicates() {
+-        let mut addrs = HashMap::new();
+-        let lh = match lookup_host("localhost") {
+-            Ok(lh) => lh,
+-            Err(e) => panic!("couldn't resolve `localhost': {}", e)
+-        };
+-        let _na = lh.map(|sa| *addrs.entry(sa).or_insert(0) += 1).count();
+-        assert!(addrs.values().filter(|&&v| v > 1).count() == 0);
+-    }
+-}

debian/patches/series

@@ -27,3 +27,6 @@ d-dynamic-link-llvm.patch
 d-use-system-jquery.patch
 d-no-web-dependencies-in-doc.patch
 d-cross-compile-install.patch
+
+# Work around for some porterboxes, keep this commented
+#d-host-duplicates.patch

debian/rules

@@ -125,6 +125,8 @@ override_dh_auto_configure: debian/config.toml
 	! grep --color=always -i 'll...?$(OLD_LLVM_VERSION)' --exclude=changelog -R debian
 	$(PRECONFIGURE_CHECK)
 	if [ -d stage0 ]; then mkdir -p build && ln -sfT ../stage0 build/cache; fi
+	# avoid having to do this manually all the time
+	if [ -n "$(shell grep "Debian .*porterbox" /etc/motd)" ]; then debian/ensure-patch -N debian/patches/d-host-duplicates.patch; fi
 	PATH="$$PWD/debian/bin:$$PATH" \
 	    ./configure $(DEB_CONFIGURE_FLAGS)