API ERRATA -- $Id$

Root Cause of Errata: incompatible
 Library(s) Affected: libsvn_wc
Function(s) Affected: svn_wc_merge_props2
                      svn_wc_merge_props
                      svn_wc_merge_prop_diffs
     New Behavior in: 1.7
      Related Issues: 953


== Details of Previous Behavior ==

The affected functions have a BASE_MERGE parameter that will cause the
function to apply the specified property changes to the pristine
("base") properties when set to TRUE.

This capability originated in r843714 (aka r3640) to solve issue #953.
Prior to that change, merges were updating the pristine properties,
and this flag enabled merge to *avoid* that effect.

The affected functions are wrappers around internal functions. The
(internal) svn_wc__merge_prop_diffs() and its later equivalent,
svn_wc__merge_props(), are used by the update editor, so its BASE_MERGE
parameter is necessary and appropriate.


== Details of New Behavior ==

Passing TRUE for BASE_MERGE to any of the affected functions, while
DRY_RUN is FALSE, will result in SVN_ERR_UNSUPPORTED_FEATURE.

The parameter has been removed from svn_wc_merge_props3().

Internal functions still support the parameter, for the benefit up the
update editor.


== Rationale for Change ==

Allowing third-party clients to alter pristine data, to a state NOT
defined by the repository could easily lead to working copy corruption
(as seen in issue #953), and potentially lead to improper changes
applied against a repository.

No good use is known, even in legacy code, for setting the BASE_MERGE
parameter to TRUE.


== Impact on API Users ==

Clients using the old (deprecated) interfaces which pass TRUE for
BASE_MERGE, and FALSE for DRY_RUN, will no longer work after an
upgrade to the 1.7 libsvn_wc library.

Subversion itself does not use this feature, nor does TortoiseSVN, nor
AnkhSVN.