refactor: err msgs 'cannot' > 'failed to'

in nearly all cases 'cannot' was used when an action was tried and
failed. 'failed to' is strictly better because:
* just because the action didn't work that time doesnt mean it
  cannot work
* it is better at drawing the users attention to a problem

1 files changed, 3 insertions, 1 deletions

diff --git a/tests/ngit_pull.rs b/tests/ngit_pull.rs
index 6637859..2fb9229 100644
--- a/tests/ngit_pull.rs
+++ b/tests/ngit_pull.rs
@@ -96,7 +96,9 @@ mod when_branch_doesnt_exist {
                 let mut p = CliTester::new_from_dir(&test_repo.dir, ["pull"]);
                 p.expect("fetching updates...\r\n")?;
                 p.expect_eventually("\r\n")?; // some updates listed here
-                p.expect("Error: cannot find proposal that matches the current branch name\r\n")?;
+                p.expect(
+                    "Error: failed to find proposal that matches the current branch name\r\n",
+                )?;
 
                 p.expect_end()?;