Files defined in SRC_URI will be copied to the build folder.

The file permission of these files is not adjusted. This results in permission errors if the source file does not have write permissions (e.g. 0400 file permission).

How to reproduce (probably not the shortest example):
---
DESCRIPTION = "Provides tests"                            
SECTION = "tests"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
PR = "r0"

SRC_URI = "file://*"

do_install() {
    # I am sure that not everything below here is needed
    # to reproduce it. It is from the original recipe.
    install -d -m 700 ${D}${ROOT_HOME}
    install -d -m 700 ${D}${ROOT_HOME}/tests
    # copy files
    cp ${WORKDIR}/*.py ${D}${ROOT_HOME}/tests/
    # fix permission
    chmod 700 ${D}${ROOT_HOME}/tests/*.py
    chown -R root:root ${D}${ROOT_HOME}/
}

FILES_${PN} = "${ROOT_HOME}/tests/"
---

Now create a file "files/test.py" with permission 0400. Run the recipe. Then modify the SRC_URI (e.g. duplicate the files to copy SRC_URI = "file://* file://*") and run the recipe again.

The file test.py can't be copied anymore because it already exists but does not have the correct file permission to overwrite.


Note: The reasons why these files don't have write permissions in my case is because we use perforce. Perforce by default does not grant write permissions to files (e.g. like git which stores the file permission of the checkin).