# zypper refresh --repo eng
Repository 'eng' is up to date.
Specified repositories have been refreshed.

# sudo zypper --verbose up --repo eng my-aix
Verbosity: 1
Non-option program arguments: 'my-aix'
Initializing Target
Loading repository data...
Reading installed packages...
Force resolution: No
No update candidate for 'my-aix-99.0.0.master-1503021820.125.noarch'. The highest available version is already installed.
Resolving package dependencies...
Force resolution: No

Nothing to do.

# zypper packages -r eng | grep my-aix
i | eng        | my-aix                | 99.0.0.master-1503021820.125 | noarch
v | eng        | my-aix                | 99.0.0.master-1503021820.124 | noarch
v | eng        | my-aix                | 99.0.0.master-1502231319.122 | noarch
v | eng        | my-aix                | 99.0.0.master-1502231319.121 | noarch
v | eng        | my-aix                | 99.0.0.master-1502231319.120 | noarch
v | eng        | my-aix                | 99.0.0.master-1502231319.119 | noarch
On the repository side:

# ls -l repo/drpms
-rw-r--r-- 1 eng users   63681 Mar  4 00:23 my-aix-99.0.0.master-1503021820.125_99.0.0.master-1503021820.126.noarch.drpm

# ls -l repodata
-rw-r--r-- 1 root root  12620 Mar  6 03:25 filelists.xml.gz
-rw-r--r-- 1 root root   4101 Mar  6 03:25 other.xml.gz
-rw-r--r-- 1 eng  users  1583 Mar  4 02:23 prestodelta.xml.gz
-rw-r--r-- 1 root root  13195 Mar  6 03:25 primary.xml.gz
-rw-r--r-- 1 root root   1152 Mar  6 03:25 repomd.xml
-rw-r--r-- 1 eng  users   197 Mar  3 23:59 repomd.xml.asc
I tried moving the delta RPM up a directory to where the regular packages are stored with the same result.

I tried changing the delta RPM extension to .rpm:

# zypper --verbose up --repo eng
Verbosity: 1
Initializing Target
Checking whether to refresh metadata for eng
Loading repository data...
Reading installed packages...
Force resolution: No

The following package is going to be upgraded:
  my-aix  99.0.0.master-1503021820.125 -> 99.0.0.master-1503021820.126

The following package is not supported by its vendor:
  my-aix  99.0.0.master-1503021820.126

1 package to upgrade.
Overall download size: 63.0 KiB. No additional space will be used or freed after the operation.
Continue? [y/n/? shows all options] (y):
Retrieving package my-aix-99.0.0.master-1503021820.126.noarch (1/1), 63.0 KiB (46.8 MiB unpacked)
Installing: my-aix-99.0.0.master-1503021820.126 [error]
Installation of my-aix-99.0.0.master-1503021820.126 failed:
(with --nodeps --force) Error: Subprocess failed. Error: RPM failed: error: my-aix-99.0.0.master-1503021820.126.noarch is a Delta RPM and cannot be directly installed
error: error reading from file /var/cache/zypp/packages/eng/my-aix-99.0.0.master-1503021820.125_99.0.0.master-1503021820.126.noarch.rpm
I have verified that the zypp.conf has support for delta RPM's enabled. I have manually run applydeltarpm to generate the full v126 package to verify that the delta RPM is valid.

Do you know where there is documentation on this subject? I have spent a long time on google without success.