Fails to detect fink interaction, terminates build premature

While building passwd-avahi, FC prematurely ends the build, and fails to detect that fink needs user interaction. Package builds correctly from command line, so this appear to be an FC issue, not fink. Transcript from command line is below. FC ends the build after the line "Setting up passwd-avahi..."

$ fink install avahi
Password:
Information about 7186 packages read in 0 seconds.
The following package will be installed or updated:
avahi
The following 4 additional packages will be installed:
libavahi-client3-shlibs libavahi-common3-shlibs libavahi-core7-shlibs
passwd-avahi
Do you want to continue? [Y/n]
Reading buildlock packages...
All buildlocks accounted for.
/sw/bin/dpkg-lockwait -i /sw/fink/dists/stable/main/binary-darwin-x86_64/base/passwd-avahi_20130111-2_darwin-x86_64.deb
(Reading database ... 204369 files and directories currently installed.)
Preparing to replace passwd-avahi 20130111-2 (using .../passwd-avahi_20130111-2_darwin-x86_64.deb) ...
Unpacking replacement passwd-avahi ...
Setting up passwd-avahi (20130111-2) ...
'avahi' group exists, with parameters:

AppleMetaNodeLocation: /Local/Default
GeneratedUID: B33F2490-06CF-4FDA-82A3-AB8CD7F43C52
Password: *
PrimaryGroupID: 274
RecordName: avahi
RecordType: dsRecTypeStandard:Groups

Fink will use these settings.

Looking for avahi entry in /sw/etc/passwd-fink...found.
624 is available. Using that for the UID.

The following user entry will be added to your DirectoryServices database:
RecordName: avahi
UniqueID: 624
PrimaryGroupID: 274
RealName: Service Discovery Daemon
NFSHomeDirectory: /dev/null
UserShell: /dev/null
Add the entry now? [Y/n]

[build continues normally without user interaction after this point]