acceptance: a later FAIL blocks inheritance, ffboot is a component, the units fallback is valid

The inheritance walk skipped every record that was not a PASS on the
current fingerprint, so a FAIL or ERROR recorded after a PASS on the
same image was stepped over and the older PASS inherited into the next
campaign. The newest record on the fingerprint now decides: a PASS is
inherited, a FAIL or ERROR blocks it (reason failed-since), an ABORTED
run says nothing. Unit tests for all three orders.

ffboot, the tool that rewrites the boot environment on every install and
slot switch, was packaged from scripts/ outside every fingerprint. It
now lives in the recipe's files and the recipe inherits the manifest
class; the tree manifest tool fingerprints file components the same
way, and the update tests cover the component.

forgectrl.settings-bounds fell back to ui_units=mm, which the whitelist
refuses, so the always-required test failed on a fresh machine; the
fallback is metric.

forgetest/forgetest/campaign.py

@@ -96,16 +96,29 @@ def compute(records, tests, manifest, catalog_hash, running=None):
         elif t.always:
             reason = "always"
         else:
+            # The newest record on the current fingerprint decides: a PASS
+            # is inherited, a FAIL or ERROR after it blocks the inheritance
+            # (the test has to be run again), an ABORTED run says nothing.
             inh = None
+            blocked = None
             for r in reversed(hist):
-                if r.get("result") != PASS or r.get("fingerprint") != fp:
+                if r.get("fingerprint") != fp:
                     continue
                 if epoch and (r.get("ts") or "") <= epoch:
                     continue
-                inh = r
-                break
+                res = r.get("result")
+                if res == PASS:
+                    inh = r
+                    break
+                if res in (FAIL, ERROR):
+                    blocked = r
+                    break
             if inh is not None:
                 status, satisfied, origin, reason = "inherited", True, inh, "inherited"
+            elif blocked is not None and any(r.get("result") == PASS and r.get("fingerprint") == fp
+                                             and (r.get("ts") or "") < (blocked.get("ts") or "")
+                                             for r in hist):
+                reason = "failed-since"
             else:
                 reason = "domain-changed" if any(r.get("result") == PASS for r in hist) else "never-passed"
         if not satisfied and last_r is not None:

forgetest/forgetest/suite/forgectrl.py

@@ -165,7 +165,7 @@ def settings_bounds(ctx):
             key = k
             break
     if key is None:
-        key, val = "ui_units", "mm"
+        key, val = "ui_units", "metric"
         ctx.log("no settable key is present; writing %s=%s (recorded in evidence)", key, val)
     else:
         val = before[key]

forgetest/forgetest/suite/update.py

@@ -5,7 +5,8 @@ import tempfile
 from ..catalog import test
 from .. import hw
 
-_UPDATE_COVERS = [("forgectrl", "src/update.c"), ("forgectrl", "src/update.h")]
+_UPDATE_COVERS = [("forgectrl", "src/update.c"), ("forgectrl", "src/update.h"),
+                  ("ffboot", "**")]
 
 
 @test("update.slots-and-signature", title="Boot slots readable, unsigned/tampered archives refused",