break out bug report

doc/bugs/get_-J_cannot_be_used_with_password-based_authentication/comment_8_5da63cf5fa93120c85b98077fba51488._comment

@@ -6,5 +6,6 @@
 Current status: It's implemented, but not for `GIT_SSH` yet.
 
 The display is a bit ugly, because the ssh password prompt line
-confuses the concurrent-output region manager.
+confuses the concurrent-output region manager. Opened
+[[minor_display_glitch_with_ssh_password_prompting_and_-J]] bug for that.
 """]]

doc/bugs/minor_display_glitch_with_ssh_password_prompting_and_-J.mdwn

@@ -0,0 +1,45 @@
+When using -J and there's a ssh password prompt (or other prompt eg ssh
+host key), the region-based display gets messed up by the ssh output. This
+is a minor display glitch; it's still fairly clear what git-annex is doing.
+
+The root problem is that the regional display code does not know the
+absolute cursor position. All cursor movement is relative. So when ssh
+display moves the cursor, all subsequent output goes to the wrong place.
+
+ansi-terminal has absolute cursor movement, but no way to query position.
+
+Some approaches to fix it:
+
+1. Allocate a slave pty and run ssh in there, forwarding IO from the slave
+   pty to the master pty. The ssh output is then added to the region that
+   it's prompting for the password for.
+   
+   Unix-specific and somewhat heavyweight solution.
+
+2. Set position to eg 0,0 when starting git-annex, and then the
+   absolute position can be calculated, and after ssh runs it can reset the
+   cursor to the previous position. 
+   
+   Would make -J take over the whole screen even if it's only transferring
+   1 file.
+
+3. Clear all regions before running the ssh command that can prompt,
+   (moving the cursor to the start of the first region),
+   and redraw them when it's done. So the ssh output would appear above the
+   redrawn regions.
+
+   This would cause some flicker in the common case where ssh does not have
+   any output. The N regions would display briefly, then be cleared, then
+   be redrawn. It might flicker multiple times, when multiple different
+   hosts are being accessed. 
+   
+   One way to avoid the flicker would be to first
+   try to ssh with password prompting disabled, and only if that fails do
+   regions need to be cleared for the ssh that will prompt. Also, since
+   we then know ssh will prompt, we can display the hostname as context for
+   the "Password:" prompt it uses.
+
+4. Find a way to add cursor position querying to ansi-terminal. Can it be
+   done portably?
+
+--[[Joey]]