scripts/oe-build-perf-report: show recipe version changes in html report

If buildstats are available (for a certain measurement), show recipe
version changes between the two builds that are being compared. The
information shown includes new and dropped recipes as well as changes in
recipe version, revision or epoch.

[YOCTO #11382]

(From OE-Core rev: 46eb839b51bb1466a9feeb09c9c437d6d45576cc)

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/buildstats.py

@@ -157,9 +157,9 @@ class BSRecipe(object):
         self.version = version
         self.revision = revision
         if epoch is None:
-            self.nevr = "{}-{}-{}".format(name, version, revision)
+            self.evr = "{}-{}".format(version, revision)
         else:
-            self.nevr = "{}-{}_{}-{}".format(name, epoch, version, revision)
+            self.evr = "{}_{}-{}".format(epoch, version, revision)
         self.tasks = {}
 
     def aggregate(self, bsrecipe):
@@ -176,6 +176,10 @@ class BSRecipe(object):
                 self.tasks[taskname] = BSTaskAggregate([self.tasks[taskname]])
             self.tasks[taskname].append(taskdata)
 
+    @property
+    def nevr(self):
+        return self.name + '-' + self.evr
+
 
 class BuildStats(dict):
     """Class representing buildstats of one build"""
@@ -323,6 +327,7 @@ class BSVerDiff(object):
         self.vchanged = {}
         self.rchanged = {}
         self.unchanged = {}
+        self.empty_diff = False
 
         common = recipes2.intersection(recipes1)
         if common:
@@ -336,3 +341,9 @@ class BSVerDiff(object):
                     self.rchanged[recipe] = rdiff
                 else:
                     self.unchanged[recipe] = rdiff
+
+        if len(recipes1) == len(recipes2) == len(self.unchanged):
+            self.empty_diff = True
+
+    def __bool__(self):
+        return not self.empty_diff