Add force-mirror FEATURE.

force-mirror: Only fetch files from configured mirrors, ignoring
SRC_URI, except when mirror is in the ebuild(5) RESTRICT variable.

TEST=Test that ebuilds now fail with FEATURES=force-mirror if files are
not in the configured mirror.

Change-Id: I8484d5af8dff97b431398030b33c024ff1295ba0

Review URL:
(cherry picked from commit 1944622240d87dfa90d88ba19d68f023eed9949f)
diff --git a/man/make.conf.5 b/man/make.conf.5
index 6a1fdd3..cbc007ff 100644
--- a/man/make.conf.5
+++ b/man/make.conf.5
@@ -304,6 +304,10 @@
 Modifies .la files to not include other .la files and some other
 fixes (order of flags, duplicated entries, ...)
+.B force\-mirror
+Only fetch files from configured mirrors, ignoring \fBSRC_URI\fR,
+except when \fImirror\fR is in the \fBebuild\fR(5) \fBRESTRICT\fR variable.
 .B lmirror
 When \fImirror\fR is enabled in \fBFEATURES\fR, fetch files even
 when \fImirror\fR is also in the \fBebuild\fR(5) \fBRESTRICT\fR variable.
diff --git a/pym/portage/ b/pym/portage/
index b2d2f77..34b02fc 100644
--- a/pym/portage/
+++ b/pym/portage/
@@ -88,8 +88,8 @@
 SUPPORTED_FEATURES       = frozenset([
                            "assume-digests", "binpkg-logs", "buildpkg", "buildsyspkg", "candy",
                            "ccache", "chflags", "collision-protect", "compress-build-logs",
-                           "digest", "distcc", "distlocks",
-                           "fakeroot", "fail-clean", "fixpackages", "getbinpkg",
+                           "digest", "distcc", "distlocks", "fakeroot",
+                           "fail-clean", "fixpackages", "force-mirror", "getbinpkg",
                            "installsources", "keeptemp", "keepwork", "fixlafiles", "lmirror",
                            "metadata-transfer", "mirror", "multilib-strict", "news",
                            "noauto", "noclean", "nodoc", "noinfo", "noman", "nostrip",
diff --git a/pym/portage/package/ebuild/ b/pym/portage/package/ebuild/
index c33375c..6e4c728 100644
--- a/pym/portage/package/ebuild/
+++ b/pym/portage/package/ebuild/
@@ -245,8 +245,8 @@
 	userpriv = secpass >= 2 and "userpriv" in features
 	# 'nomirror' is bad/negative logic. You Restrict mirroring, not no-mirroring.
-	if "mirror" in restrict or \
-	   "nomirror" in restrict:
+	restrict_mirror = "mirror" in restrict or "nomirror" in restrict
+	if restrict_mirror:
 		if ("mirror" in features) and ("lmirror" not in features):
 			# lmirror should allow you to bypass mirror restrictions.
 			# XXX: This is not a good thing, and is temporary at best.
@@ -344,8 +344,7 @@
 	if "local" in custommirrors:
 		mymirrors += custommirrors["local"]
-	if "nomirror" in restrict or \
-	   "mirror" in restrict:
+	if restrict_mirror:
 		# We don't add any mirrors.
@@ -374,6 +373,7 @@
 			del mymirrors[x]
 	restrict_fetch = "fetch" in restrict
+	force_mirror = "force-mirror" in features and not restrict_mirror
 	custom_local_mirrors = custommirrors.get("local", [])
 	if restrict_fetch:
 		# With fetch restriction, a normal uri may only be fetched from
@@ -430,7 +430,7 @@
 				writemsg(_("Invalid mirror definition in SRC_URI:\n"), noiselevel=-1)
 				writemsg("  %s\n" % (myuri), noiselevel=-1)
-			if restrict_fetch:
+			if restrict_fetch or force_mirror:
 				# Only fetch from specific mirrors is allowed.
 			if "primaryuri" in restrict: