compiletest: properly handle revisioned run-rustfix tests

tests/ui/compiletest-self-test/run-rustfix-revisions.foo.fixed

@@ -0,0 +1,9 @@
+// Check that revisioned `run-rustfix` does not fail with issues related to `.` in crate name.
+//@ revisions: foo
+//@[foo] run-rustfix
+#![deny(unused_variables)]
+
+fn main() {
+    let _x = 0usize;
+    //~^ ERROR unused variable: `x`
+}

tests/ui/compiletest-self-test/run-rustfix-revisions.foo.stderr

@@ -0,0 +1,14 @@
+error: unused variable: `x`
+  --> $DIR/run-rustfix-revisions.rs:7:9
+   |
+LL |     let x = 0usize;
+   |         ^ help: if this is intentional, prefix it with an underscore: `_x`
+   |
+note: the lint level is defined here
+  --> $DIR/run-rustfix-revisions.rs:4:9
+   |
+LL | #![deny(unused_variables)]
+   |         ^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+

tests/ui/compiletest-self-test/run-rustfix-revisions.rs

@@ -0,0 +1,9 @@
+// Check that revisioned `run-rustfix` does not fail with issues related to `.` in crate name.
+//@ revisions: foo
+//@[foo] run-rustfix
+#![deny(unused_variables)]
+
+fn main() {
+    let x = 0usize;
+    //~^ ERROR unused variable: `x`
+}