fix issue with rc parsing (#266)

* fix issue with rc parsing

* buildify
diff --git a/rules/rbe_repo.bzl b/rules/rbe_repo.bzl
index 800c92d..750b128 100644
--- a/rules/rbe_repo.bzl
+++ b/rules/rbe_repo.bzl
@@ -311,9 +311,9 @@
     # If a specific Bazel and Bazel RC version is specified, install that version.
     bazel_url = "https://releases.bazel.build/" + bazel_version
     if bazel_rc_version:
-        bazel_url += ("/rc" + bazel_rc_version +
+        bazel_url += ("/rc" + str(bazel_rc_version) +
                       "/bazel-" + bazel_version + "rc" +
-                      bazel_rc_version)
+                      str(bazel_rc_version))
     else:
         bazel_url += "/release/bazel-" + bazel_version
     bazel_url += "-installer-linux-x86_64.sh"
@@ -433,7 +433,7 @@
     # run run_and_extract.sh
     print("Running container")
     result = ctx.execute(["./run_and_extract.sh"])
-    _print_exec_results("run_and_extract", result)
+    _print_exec_results("run_and_extract", result, fail_on_error = True)
 
     # Expand outputs inside this remote repo
     result = ctx.execute(["tar", "-xf", "output.tar"])
diff --git a/rules/version_check.bzl b/rules/version_check.bzl
index 1ee6427..b5cc986 100644
--- a/rules/version_check.bzl
+++ b/rules/version_check.bzl
@@ -20,13 +20,14 @@
 def parse_rc(bazel_version):
     if bazel_version.find("rc") != -1:
         rc = ""
-        for i in range(len(bazel_version) - bazel_version.find("rc")):
-            c = bazel_version[i]
+        for i in range(len(bazel_version) - bazel_version.find("rc") - 2):
+            c = bazel_version[i + bazel_version.find("rc") + 2]
             if not c.isdigit():
                 if rc == "":
                     return -1
-                return int(rc)
+                break
             rc += c
+        return int(rc)
 
 def _check_bazel_version(bazel_version_fallback):
     if "bazel_version" not in dir(native):