clone: add tests for unsafe ssh url (SEC)

tests/test-clone.t

@@ -1092,3 +1092,25 b' pooled".'
   adding remote bookmark bookA
   updating working directory
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+SEC: check for unsafe ssh url
+
+  $ hg clone 'ssh://-oProxyCommand=touch${IFS}owned/path'
+  abort: potentially unsafe url: 'ssh://-oProxyCommand=touch${IFS}owned/path'
+  [255]
+  $ hg clone 'ssh://%2DoProxyCommand=touch${IFS}owned/path'
+  abort: potentially unsafe url: 'ssh://-oProxyCommand=touch${IFS}owned/path'
+  [255]
+  $ hg clone 'ssh://fakehost|shellcommand/path'
+  abort: potentially unsafe url: 'ssh://fakehost|shellcommand/path'
+  [255]
+  $ hg clone 'ssh://fakehost%7Cshellcommand/path'
+  abort: potentially unsafe url: 'ssh://fakehost|shellcommand/path'
+  [255]
+
+  $ hg clone 'ssh://-oProxyCommand=touch [e-mail]/nonexistent/path'
+  abort: potentially unsafe url: 'ssh://-oProxyCommand=touch owned [e-mail]/nonexistent/path'
+  [255]
+We should not have created a file named owned - if it exists, the
+attack succeeded.
+  $ if test -f owned; then echo 'you got owned'; fi