buildman: Correct counting of build failures on retry

When a build is to be performed, buildman checks to see if it has already
been done. In most cases it will not bother trying again. However, it was
not reading the return code from the 'done' file, so if the result was a
failure, it would not be counted. This depresses the 'failure' count stats
that buildman prints in this case.

Fix this bug by always reading the return code.
Signed-off-by: NSimon Glass <sjg@chromium.org>

tools/buildman/builderthread.py

@@ -138,16 +138,17 @@ class BuilderThread(threading.Thread):
         result.already_done = os.path.exists(done_file)
         will_build = (force_build or force_build_failures or
             not result.already_done)
-        if result.already_done and will_build:
+        if result.already_done:
             # Get the return code from that build and use it
             with open(done_file, 'r') as fd:
                 result.return_code = int(fd.readline())
-            err_file = self.builder.GetErrFile(commit_upto, brd.target)
-            if os.path.exists(err_file) and os.stat(err_file).st_size:
-                result.stderr = 'bad'
-            elif not force_build:
-                # The build passed, so no need to build it again
-                will_build = False
+            if will_build:
+                err_file = self.builder.GetErrFile(commit_upto, brd.target)
+                if os.path.exists(err_file) and os.stat(err_file).st_size:
+                    result.stderr = 'bad'
+                elif not force_build:
+                    # The build passed, so no need to build it again
+                    will_build = False
 
         if will_build:
             # We are going to have to build it. First, get a toolchain