www/firefox: unbreak fetch

See https://bugzilla.mozilla.org/show_bug.cgi?id=1432591#c22

• mozilla-release-239e434d6d2b8e1e2b697c3416d1e96d48fe98e5.old/.hg_archival.txt 2018-03-22 20:46:41 UTC

+++ mozilla-release-239e434d6d2b8e1e2b697c3416d1e96d48fe98e5/.hg_archival.txt 2018-03-22 20:46:41 UTC
@@ -1,7 +1,7 @@
repo: 8ba995b74e18334ab3707f27e9eb8f4e37ba3d29
node: 239e434d6d2b8e1e2b697c3416d1e96d48fe98e5
branch: default
-latesttag: FENNEC_59_0_1_BUILD2
-latesttag: FENNEC_59_0_1_RELEASE
-latesttagdistance: 18
-changessincelatesttag: 18
+tag: FENNEC_59_0_2_BUILD1
+tag: FENNEC_59_0_2_RELEASE
+tag: FIREFOX_59_0_2_BUILD1
+tag: FIREFOX_59_0_2_RELEASE