[PATCH v3] push: Enhance unspecified push default warning

When the unset push.default warning message is displayed
this may be the first time many users encounter push.default.
Modified the warning message to explain in a compact
manner what push.default is and why it is being changed in
Git 2.0.  Also provided additional information to help users
decide if this change will affect their workflow.

Signed-off-by: Greg Jacobson <redacted>
---
 builtin/push.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/builtin/push.c b/builtin/push.c
index 7b1b66c..5393e28 100644
--- a/builtin/push.c
+++ b/builtin/push.c

@@ -174,6 +174,15 @@ N_("push.default is unset; its implicit value is

changing in\n"
    "\n"
    "  git config --global push.default simple\n"
    "\n"
+   "When push.default is set to 'matching', git will push all local branches\n"
+   "to the remote branches with the same (matching) name.  This will no\n"
+   "longer be the default in Git 2.0 because a branch could be\n"
+   "unintentionally pushed to a remote.\n"
+   "\n"
+   "In Git 2.0 the new push.default of 'simple' will push only the current\n"
+   "branch to the same remote branch used by git pull.   A push will\n"
+   "only succeed if the remote and local branches have the same name.\n"
+   "\n"
    "See 'git help config' and search for 'push.default' for further
information.\n"
    "(the 'simple' mode was introduced in Git 1.7.11. Use the similar mode\n"
    "'current' instead of 'simple' if you sometimes use older versions
of Git)");
--
1.8.4.474.g128a96c.dirty