When started with klauncher (Alt+F2), kdesu hangs for 60s before showing the password prompt. The symptom is absent when launching kdesu from console (yakuake).

Attached strace indicates it waits through a 30s timeout on two separate occasions. For quick reference, here are apparently relevant pieces:

     0.000000 write(2, "QProcess: Destroyed while proces"..., 52) = 52
     0.000000 kill(5080, SIGKILL)       = 0
     0.000000 clock_gettime(CLOCK_MONOTONIC, {3734, 875327188}) = 0
     0.000000 clock_gettime(CLOCK_MONOTONIC, {3734, 875327188}) = 0
     0.000000 clock_gettime(CLOCK_MONOTONIC, {3734, 875327188}) = 0
     0.000000 select(23, [22], [], NULL, {30, 0}) = 0 (Timeout)
    30.033114 write(3, "\1\0\0\0\0\0\0\0", 8) = 8
     0.000000 close(10)                 = 0
     0.000000 close(23)                 = 0
     0.000000 close(22)                 = 0
     0.000000 access("false", X_OK)     = -1 ENOENT (No such file or directory)
     0.000000 stat("/usr/lib/kde4/libexec/su", 0x7fff754b2680) = -1 ENOENT (No such file or directory)
     0.000000 stat("/usr/local/sbin/su", 0x7fff754b2680) = -1 ENOENT (No such file or directory)
     0.000000 stat("/usr/local/bin/su", 0x7fff754b2680) = -1 ENOENT (No such file or directory)
     0.000000 stat("/usr/bin/su", {st_mode=S_IFREG|S_ISUID|0755, st_size=27608, ...}) = 0

... and ...

     0.103332 write(2, "QProcess: Destroyed while proces"..., 52) = 52
     0.000000 kill(5112, SIGKILL)       = 0
     0.000000 clock_gettime(CLOCK_MONOTONIC, {3765, 168439054}) = 0
     0.000000 clock_gettime(CLOCK_MONOTONIC, {3765, 168439054}) = 0
     0.000000 clock_gettime(CLOCK_MONOTONIC, {3765, 168439054}) = 0
     0.000000 select(25, [24], [], NULL, {30, 0}) = 0 (Timeout)
    30.036409 write(3, "\1\0\0\0\0\0\0\0", 8) = 8
     0.000000 close(12)                 = 0
     0.000000 close(25)                 = 0
     0.000000 close(24)                 = 0
     0.000000 getuid()                  = 1000
     0.000000 geteuid()                 = 1000
     0.000000 open("/etc/passwd", O_RDONLY|O_CLOEXEC) = 11


Reproducible: Always

Steps to Reproduce:
1. Open klauncher (Alt+F2)
2. Type kdesu dolphin and press enter

Actual Results:  
Kdesu prompt appears after ~60s

Expected Results:  
Kdesu prompt should appear ~immediately