Install fails if target file is read only

When trying to install a file which is marked as read-only, installation fails if the file was changed but a previous read-only copy already exists at the target location. This scenario can easily happen with SCCM systems like Perforce, where unmodified checked-out files always are marked as read-only.

Example: Given the following QBS code:

Product {
    Group {
        name: "MyFiles"
        qbs.install: true
        qbs.installDir: "my_target"
        files : [ "my.file" ]
    }
}

When executing "install" on this, my.file is copied to my_target. However, since the source file was checked-out from Perforce, it is marked as read-only. After copying it to the target, the copy of my.file also is marked as read-only. Now if the source changes for some reason and "install" is executed again, it fails with this error message:

:-1: error: Installation error: Could not copy file 'my_source\my.file' to 'my_target\my.file'. Destination file exists

If the read-only mark is manually removed from the target, everything works fine. My suggestion would be to always remove the read-only mark after copying.