testsuite: APPL and Icon operations fail with mysql backend

[rdmark]

The following testsuite tests fail when using the mysql CNID backend

• FPGetIcon:test115: get Icon call
• FPGetAPPL:test169: test appl
• FPAddIcon:test212: Add Icon call
• FPGetIconInfo:test213: get Icon Info call
• FPAddAPPL:test214: test appl
• FPRemoveAPPL:test215: remove appl

Example afpd log from test115

netatalk-1  | Apr 19 09:10:08.205612 afpd[220] {dsi_tcp.c:232} (info:DSI): AFP/TCP session from 172.18.0.1:46554
netatalk-1  | Apr 19 09:10:08.208483 afpd[220] {uams_pam.c:143} (info:ad): cleartext login: atalk1
netatalk-1  | Apr 19 09:10:08.273007 afpd[220] {auth.c:245} (note:AFPDaemon): Login by atalk1 (AFP3.4)
netatalk-1  | Apr 19 09:10:08.274208 afpd[224] {dsi_tcp.c:232} (info:DSI): AFP/TCP session from 172.18.0.1:46566
netatalk-1  | Apr 19 09:10:08.278501 afpd[224] {uams_pam.c:143} (info:ad): cleartext login: atalk2
netatalk-1  | Apr 19 09:10:08.323342 afpd[224] {auth.c:245} (note:AFPDaemon): Login by atalk2 (AFP3.4)
netatalk-1  | Apr 19 09:10:08.326034 afpd[220] {cnid_mysql.c:239} (info:CNID): MySQL query "INSERT INTO volumes (VolUUID,Volpath,Stamp,Depleted) VALUES('E79A1850449A7BD415B7361658FCF584','/mnt/afpshare','phh\0\0\0\0',0)", error: Duplicate entry 'E79A1850449A7BD415B7361658FCF584' for key 'PRIMARY'
netatalk-1  | Apr 19 09:10:08.327593 afpd[220] {desktop.c:311} (error:AFPDaemon): iconopen(/var/local/netatalk/CNID//test1//.AppleDesktop/t/ttxt.icon): open: No such file or directory
netatalk-1  | Apr 19 09:10:08.327605 afpd[220] {desktop.c:481} (error:AFPDaemon): afp_addicon(/var/local/netatalk/CNID//test1//.AppleDesktop/t/ttxt.icon): write: Bad file descriptor