In the following scenario: 1. Start mergemaster 2. Interrupt it 3. < Somehow the temproot directory disappears > 4. mergemaster -r Many bad things can happen, especially if the -i option is in use.
In the following scenario:
1. Start mergemaster
2. Interrupt it
3. < Somehow the temproot directory disappears >
4. mergemaster -r
Many bad things can happen, especially if the -i option is in use.

Therefore, add a check to make sure it still exists before we start
comparing files.

Brought to my attention by:
PR:		bin/40538
Submitted by:	Cyrille Lefevre <cyrille.lefevre@laposte.net>

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase