Fix test failures

One of these days I'll release a patch version without breaking the
build...

Author: sgrif

diesel_compile_tests/Cargo.toml

@@ -11,6 +11,6 @@ diesel_codegen = { version = "0.15.0" }
 compiletest_rs = "=0.2.7"
 
 [replace]
-"diesel:0.15.1" = { path = "../diesel" }
+"diesel:0.15.2" = { path = "../diesel" }
 "diesel_codegen:0.15.0" = { path = "../diesel_codegen" }
 "diesel_infer_schema:0.15.0" = { path = "../diesel_infer_schema" }