Auto merge of #5104 - Eh2406:bug_fix, r=alexcrichton

missed this important bug

In the PR #5000 I finished and we merged yesterday I missed a bug and left in an outdated comment.

@alexcrichton

Author: bors

src/cargo/core/resolver/mod.rs

@@ -778,8 +778,6 @@ fn activate_deps_loop<'a>(
                     &mut remaining_candidates,
                     &mut conflicting_activations,
                 ).ok_or_else(|| {
-                    // if we hit an activation error and we are out of other combinations
-                    // then just report that error
                     activation_error(
                         &cx,
                         registry,
@@ -827,8 +825,13 @@ fn activate_deps_loop<'a>(
 
             // Add an entry to the `backtrack_stack` so
             // we can try the next one if this one fails.
-            if has_another && successfully_activated {
-                backtrack_stack.push(backtrack);
+            if successfully_activated {
+                if has_another {
+                    backtrack_stack.push(backtrack);
+                }
+            } else {
+                // `activate` changed `cx` and then failed so put things back.
+                cx = backtrack.context_backup;
             }
         }
     }

tests/testsuite/generate_lockfile.rs

@@ -88,7 +88,7 @@ fn no_index_update() {
         .build();
 
     assert_that(p.cargo("generate-lockfile"),
-                execs().with_status(0).with_stdout("")
+                execs().with_stdout("")
                     .with_stderr_contains("    Updating registry `https://github.com/rust-lang/crates.io-index`"));
 
     assert_that(p.cargo("generate-lockfile").masquerade_as_nightly_cargo().arg("-Zno-index-update"),