cargo test -p foo ignores [dev-dependendencies]

[SimonSapin]

Test case:

cargo new a
cargo new a/b
echo 'b = {path = "./b"}'>>a/Cargo.toml
echo '[dev-dependencies]'>>a/b/Cargo.toml
echo 'matches = "*"'>>a/b/Cargo.toml
echo '#[cfg(test)] extern crate matches;'>>a/b/src/lib.rs
(cd a && cargo test -v -p b)
rm -r a

Output with cargo 0.11.0-nightly (6151a85 2016-04-25):

   Compiling b v0.1.0 (file:///tmp/aaa/a/b)
     Running `rustc b/src/lib.rs --crate-name b --crate-type lib -g --test -C metadata=75e04c9cbb004a98 -C extra-filename=-75e04c9cbb004a98 --out-dir /tmp/aaa/a/target/debug/deps --emit=dep-info,link -L dependency=/tmp/aaa/a/target/debug/deps -L dependency=/tmp/aaa/a/target/debug/deps`
     Running `rustc b/src/lib.rs --crate-name b --crate-type lib -g -C metadata=6811c2c4848be05c -C extra-filename=-6811c2c4848be05c --out-dir /tmp/aaa/a/target/debug/deps --emit=dep-info,link -L dependency=/tmp/aaa/a/target/debug/deps -L dependency=/tmp/aaa/a/target/debug/deps`
b/src/lib.rs:7:14: 7:35 error: can't find crate for `matches` [E0463]
b/src/lib.rs:7 #[cfg(test)] extern crate matches;
                            ^~~~~~~~~~~~~~~~~~~~~
error: aborting due to previous error
Build failed, waiting for other jobs to finish...
error: Could not compile `b`.

Caused by:
  Process didn't exit successfully: `rustc b/src/lib.rs --crate-name b --crate-type lib -g --test -C metadata=75e04c9cbb004a98 -C extra-filename=-75e04c9cbb004a98 --out-dir /tmp/aaa/a/target/debug/deps --emit=dep-info,link -L dependency=/tmp/aaa/a/target/debug/deps -L dependency=/tmp/aaa/a/target/debug/deps` (exit code: 101)

(Using (cd a/b && cargo test -v) instead works as expected, but uses a different target directory.)

[alexcrichton]

I believe that this is a dupe of #860, but thanks for the report!

[alexcrichton]

(also note that this should be fixed with workspaces)