Moved _write_version from prerelease to baserelease.

Will be used by bumpversion command too.
Note that postrelease has its own version.

zest/releaser/baserelease.py

@@ -234,6 +234,14 @@ def _check_required(self):
                 default=False):
             sys.exit(1)
 
+    def _write_version(self):
+        if self.data['new_version'] != self.data['original_version']:
+            # self.vcs.version writes it to the file it got the version from.
+            self.vcs.version = self.data['new_version']
+            logger.info("Changed version from %s to %s",
+                        self.data['original_version'],
+                        self.data['new_version'])
+
     def _write_history(self):
         """Write previously-calculated history lines back to the file"""
         if self.data['history_file'] is None:

zest/releaser/prerelease.py

@@ -115,14 +115,6 @@ def _grab_version(self, initial=False):
         self.data['original_version'] = original_version
         self.data['new_version'] = new_version
 
-    def _write_version(self):
-        if self.data['new_version'] != self.data['original_version']:
-            # self.vcs.version writes it to the file it got the version from.
-            self.vcs.version = self.data['new_version']
-            logger.info("Changed version from %s to %s",
-                        self.data['original_version'],
-                        self.data['new_version'])
-
 
 def datacheck(data):
     """Entrypoint: ensure that the data dict is fully documented"""