As per the issue description, the issue can be replicated when anonymous access has been revoked from both global and plan level permissions. After that, any triggers will fail and trying to do a manual test by running the wget command fail with 302 code as below:
C:\Program Files (x86)\GnuWin32\bin>wget --timeout=10 -t1 http:SYSTEM_WGETRC = c:/progra~1/wget/etc/wgetrc
syswgetrc = C:\Program Files (x86)\GnuWin32/etc/wgetrc
--2013-02-22 18:25:04-- http:Resolving localhost... 127.0.0.1, ::1
Connecting to localhost|127.0.0.1|:10440... connected.
HTTP request sent, awaiting response... 302 Found
Location: http:--2013-02-22 18:25:04-- http:Reusing existing connection to localhost:10440.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]
Saving to: `userlogin!default.action;jsessionid=191ud808wgqik101mmdsvq2yw4@os_destination=%2FupdateAndBuild.action%3FbuildKey=TESTA-TSTA'
[ <=> ] 10,073 --.-K/s in 0s
2013-02-22 18:25:04 (422 MB/s) - `userlogin!default.action;jsessionid=191ud808wgqik101mmdsvq2yw4@os_destination=%2FupdateAndBuild.action%3FbuildKey=TESTA-TSTA' saved [10073]
This is happening on Bamboo 4.4.x and is not replicable on older versions such as 4.3.x
Workaround
Append authentication credentials to the repository scripts os_authtype=basic&os_username=your_username&os_password=blah. Therefore something like this should work wget --timeout=10 -t1 http://localhost:10440/bamboo44/updateAndBuild.action?buildKey=TESTA-TSTA?os_authtype=basic&os_username=your_username&os_password=blah
REST endpoint should be used to trigger change detection: