"Ant debug" output always shows no changes. How can I force apkbuilder to build APK?

"Ant debug" output always shows no changes. How can I force apkbuilder to
build APK?

When I type "ant debug" on Jenkins, I always get message like :
[aapt] No changed resources. R.java and Manifest.java untouched.
[dex] No new compiled code. No need to convert bytecode to dalvik format.
[aapt] No changed resources or assets.
[apkbuilder] No changes. No need to create apk.
The same command from my local computer against the same code from Eclipse
does not output the messages above. And it always finds modified input and
creates an apk with debug key correctly from command-line. My goal is to
create an APK with debug key on Jenkins also.
Any idea why "ant debug" is showing the output as following? Is there a
way to force apkbuilder to create an apk?
-code-gen:
[mergemanifest] No changes in the AndroidManifest files.
[echo] Handling aidl files...
[aidl] No AIDL files to compile.
[echo] ----------
[echo] Handling RenderScript files...
[renderscript] No RenderScript files to compile.
[echo] ----------
[echo] Handling Resources...
[aapt] No changed resources. R.java and Manifest.java untouched.
[echo] ----------
[echo] Handling BuildConfig class...
[buildconfig] No need to generate new BuildConfig.
-pre-compile:
-compile:
-post-compile:
-obfuscate:
-dex:
[dex] input:
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/bin/classes
[dex] input:
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/libs/Robotium.jar
[dex] Using Pre-Dexed Robotium-764572c80737d765208bdb367579ac89.jar
<-
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/libs/Robotium.jar
[dex] No new compiled code. No need to convert bytecode to dalvik
format.
-crunch:
[crunch] Crunching PNG Files in source dir:
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/res
[crunch] To destination dir:
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/bin/res
[crunch] Crunched 0 PNG files to update cache
-package-resources:
[aapt] No changed resources or assets. Settings_Tests_New.ap_ remains
untouched
-package:
[apkbuilder] No changes. No need to create apk.
-post-package:
-do-debug:
[zipalign] Run cancelled: no changes to input file
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/bin/Settings_Tests_New-debug-unaligned.apk
[echo] Debug Package:
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/bin/Settings_Tests_New-debug.apk
[propertyfile] Updating property file:
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/bin/build.prop
[propertyfile] Updating property file:
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/bin/build.prop
[propertyfile] Updating property file:
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/bin/build.prop
[propertyfile] Updating property file:
/Users/buildmaster/.jenkins/workspace/my-ci-job-name/bin/build.prop
-post-build:
debug:
BUILD SUCCESSFUL