Bug 1472857 - Allow rustc 1.27 to build in automation for the sake of the base-toolchains build. r=glandium

MozReview-Commit-ID: EQj9aLbbckA

--HG--
extra : rebase_source : 072ec286faefb00480ab51e099a36636cb05233b

toolkit/library/rust/shared/build.rs

@@ -12,7 +12,9 @@ fn main() {
     } else if ver >= Version::parse("1.28.0-alpha").unwrap() && ver < Version::parse("1.29.0").unwrap() {
         println!("cargo:rustc-cfg=feature=\"oom_with_hook\"");
         bootstrap = true;
-    } else if std::env::var("MOZ_AUTOMATION").is_ok() {
+    } else if std::env::var("MOZ_AUTOMATION").is_ok() && ver >= Version::parse("1.29.0-alpha").unwrap() {
+        // For the sake of the base-toolchains build we allow building with 1.27, but
+        // retain this check for newer versions.
         panic!("Builds on automation must use a version of rust that supports OOM hooking")
     }