bundle2: support for bundling parameter value

Parameter can now have a value. We use a `<name>=<value>` form inspired from
capabilities.

There is still no kind of escaping in the name or value, yet.

mercurial/bundle2.py

@@ -42,9 +42,8 b' Binary format is as follow'
   A blob of `params size` containing the serialized version of all stream level
   parameters.
 
-  The blob contains a space separated list of parameters.
-
-  Parameter value are not supported yet.
+  The blob contains a space separated list of parameters. parameter with value
+  are stored in the form `<name>=<value>`.
 
   Special character in param name are not supported yet.
 
@@ -116,11 +115,11 b' class bundle20(object):'
     def _paramchunk(self):
         """return a encoded version of all stream parameters"""
         blocks = []
-        for key, value in self._params:
-            # XXX no support for value yet
-            assert value is None
+        for par, value in self._params:
             # XXX no escaping yet
-            blocks.append(key)
+            if value is not None:
+                par = '%s=%s' % (par, value)
+            blocks.append(par)
         return ' '.join(blocks)
 
 class unbundle20(object):

tests/test-bundle2.t

@@ -21,7 +21,9 b' Create an extension to test bundle2 API'
   >     """write a bundle2 container on standard ouput"""
   >     bundler = bundle2.bundle20()
   >     for p in opts['param']:
-  >         bundler.addparam(p)
+  >         p = p.split('=', 1)
+  >         bundler.addparam(*p)
+  > 
   >     for chunk in bundler.getchunks():
   >         ui.write(chunk)
   > 
@@ -110,3 +112,11 b' Test unbundling'
   - meal
   parts count:   0
 
+advisory parameters, with value
+-------------------------------
+
+Test generation
+
+  $ hg bundle2 --param 'caution' --param 'meal=vegan' --param 'elephants'
+  HG20\x00\x1ccaution meal=vegan elephants\x00\x00 (no-eol) (esc)
+