coverage: Only merge adjacent coverage spans

This also removes some manipulation of the function signature span that only
made sense in the context of merging non-adjacent spans.

1 files changed, 2 insertions, 1 deletions

diff --git a/tests/coverage/async_closure.coverage b/tests/coverage/async_closure.coverage
index 5aed131de2e..14f043415ea 100644
--- a/tests/coverage/async_closure.coverage
+++ b/tests/coverage/async_closure.coverage
@@ -8,7 +8,8 @@
    LL|      1|}
    LL|       |
    LL|      1|pub fn main() {
-   LL|      2|    let async_closure = async || {};
+   LL|      3|    let async_closure = async || {};
+                      ^1
   ------------------
   | async_closure::main::{closure#0}:
   |   LL|      1|    let async_closure = async || {};