convert: change default for git rename detection to 50%

This default mirrors the default for 'git diff'. Other commands have slightly
different defaults -- for example, the move/copy detection for 'git blame'
assumes that a hunk is moved if more than 40 alphanumeric characters are the
same, or copied if more than 20 alphanumeric characters are the same. 50% seems
to be the most common default, though.

hgext/convert/__init__.py

@@ -298,7 +298,7 b' def convert(ui, src, dest=None, revmapfi'
         percentage between ``0`` (disabled) and ``100`` (files must be
         identical). For example, ``90`` means that a delete/add pair will
         be imported as a rename if more than 90% of the file hasn't
-        changed. The default is ``0``.
+        changed. The default is ``50``.
 
     :convert.git.findcopiesharder: while detecting copies, look at all
         files in the working copy instead of just changed ones. This

hgext/convert/git.py

@@ -94,7 +94,8 b' class convert_git(converter_source):'
         if not os.path.exists(path + "/objects"):
             raise NoRepo(_("%s does not look like a Git repository") % path)
 
-        similarity = ui.configint('convert', 'git.similarity', default=0)
+        # The default value (50) is based on the default for 'git diff'.
+        similarity = ui.configint('convert', 'git.similarity', default=50)
         if similarity < 0 or similarity > 100:
             raise util.Abort(_('similarity must be between 0 and 100'))
         if similarity > 0:

tests/test-convert.t

@@ -252,7 +252,7 b''
                     (disabled) and "100" (files must be identical). For example,
                     "90" means that a delete/add pair will be imported as a
                     rename if more than 90% of the file hasn't changed. The
-                    default is "0".
+                    default is "50".
       convert.git.findcopiesharder
                     while detecting copies, look at all files in the working
                     copy instead of just changed ones. This is very expensive