WIP debugging what is going wrong with CI's attempt to run the test.

Author: pnkfelix

tests/common/command_invocation.rs

@@ -1,3 +1,4 @@
+use std::fs;
 use std::path::Path;
 use std::process::{Command, ExitStatus};
 
@@ -19,9 +20,11 @@ impl<'a> Context<'a> {
             command.arg(param);
         }
         let dir = self.dir;
+        fs::create_dir_all(dir)?;
         println!("running `cargo-bisect-rustc {}` in {:?}",
                  self.cli_params.join(" "),
                  dir.display());
+        assert!(dir.exists());
         let output = command.current_dir(dir).output()?;
 
         let stderr = String::from_utf8_lossy(&output.stderr);