mq: improve qclone error handling when patch directory is not a repository.

hgext/mq.py

@@ -1478,11 +1478,20 b' def clone(ui, source, dest=None, **opts)'
 
     Source patch repository is looked for in <src>/.hg/patches by
     default.  Use -p <url> to change.
+
+    The patch directory must be a nested mercurial repository, as
+    would be created by qinit -c.
     '''
     cmdutil.setremoteconfig(ui, opts)
     if dest is None:
         dest = hg.defaultdest(source)
     sr = hg.repository(ui, ui.expandpath(source))
+    patchdir = opts['patches'] or (sr.url() + '/.hg/patches')
+    try:
+        pr = hg.repository(ui, patchdir)
+    except hg.RepoError:
+        raise util.Abort(_('versioned patch repository not found'
+                           ' (see qinit -c)'))
     qbase, destrev = None, None
     if sr.local():
         if sr.mq.applied:

tests/test-mq

@@ -368,10 +368,17 b' cd qclonesource'
 echo foo > foo
 hg add foo
 hg ci -m 'add foo'
-hg qinit -c
+hg qinit
 hg qnew patch1
 echo bar >> foo
 hg qrefresh -m 'change foo'
+cd ..
+
+# repo with unversioned patch dir
+hg qclone qclonesource failure
+
+cd qclonesource
+hg qinit -c
 hg qci -m checkpoint
 qlog
 cd ..

tests/test-mq.out

@@ -407,6 +407,8 b' date: Thu Jan 01 00:00:00 1970 +0'
 summary:     add foo
 
 % qclone
+abort: versioned patch repository not found (see qinit -c)
+adding .hg/patches/patch1
 main repo:
     rev 1: change foo
     rev 0: add foo