[PATCH] siggen: Make it clear why nostamp tasks signatures don't match

[Richard Purdie <richard.purdie@linuxfoundation.org>]

If you run bitbake-diffsigs against two differing sigdata files from
nostamp tasks it shows no difference despite the differing checksum.

Change the code so this shows up as a nostamp 'taint' and at least
makes the issue clearer to the end user.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/bitbake/lib/bb/siggen.py b/bitbake/lib/bb/siggen.py
index 2985272..0352e45 100644
--- a/bitbake/lib/bb/siggen.py
+++ b/bitbake/lib/bb/siggen.py
@@ -80,6 +80,7 @@ class SignatureGeneratorBasic(SignatureGenerator):
         self.taskdeps = {}
         self.runtaskdeps = {}
         self.file_checksum_values = {}
+        self.taints = {}
         self.gendeps = {}
         self.lookupcache = {}
         self.pkgnameextract = re.compile("(?P<fn>.*)\..*")
@@ -199,11 +200,14 @@ class SignatureGeneratorBasic(SignatureGenerator):
         if 'nostamp' in taskdep and task in taskdep['nostamp']:
             # Nostamp tasks need an implicit taint so that they force any dependent tasks to run
             import uuid
-            data = data + str(uuid.uuid4())
+            taint = str(uuid.uuid4())
+            data = data + taint
+            self.taints[k] = "nostamp:" + taint
 
         taint = self.read_taint(fn, task, dataCache.stamp[fn])
         if taint:
             data = data + taint
+            self.taints[k] = taint
             logger.warn("%s is tainted from a forced run" % k)
 
         h = hashlib.md5(data).hexdigest()
@@ -247,6 +251,10 @@ class SignatureGeneratorBasic(SignatureGenerator):
         if taint:
             data['taint'] = taint
 
+        if runtime and k in self.taints:
+            if 'nostamp:' in self.taints[k]:
+                data['taint'] = self.taints[k]
+
         fd, tmpfile = tempfile.mkstemp(dir=os.path.dirname(sigfile), prefix="sigtask.")
         try:
             with os.fdopen(fd, "wb") as stream: