programs: mercurial: add "qcat" alias

hosts/common/programs/mercurial/hgrc

@@ -14,11 +14,17 @@ git = True
 # unified = 10
 
 [alias]
+noop = !$HG > /dev/null
 q = qseries -s -v
 #
+# `hg qpath`: print the path to the current queue
+qpath = !$HG noop ; echo ".hg/patches-$($HG qqueue --active)" | sed 's:hg/patches-patches:hg/patches:'
+#
+# `hg qcat PATCH_NAME`: view the diff of a mq patch in the current queue.
+qcat = !$HG noop ; cat $($HG qpath)/$1
+#
 # `hg qdup NEW_QUEUE_NAME`: copy all patches in the current queue into a new queue
-# current queue must not be named "patches"
-qdup = !$HG qq --active > /tmp/hg.active ; $HG qpop -a ; cp -R .hg/patches-$(cat /tmp/hg.active) .hg/patches-$1 ; echo $1 >> .hg/patches.queues ; $HG qq $1
+qdup = !$HG qpop -a ; cp -R $($HG qpath) .hg/patches-$1 ; echo $1 >> .hg/patches.queues ; $HG qqueue $1
 qstat = qdiff --stat
 sblame = blame -undq
 #