I created a user with the following ldif:

dn: cn=dgoetz,ou=users,dc=localdomain
objectClass: inetOrgPerson
cn: dgoetz
sn: Goetz
description: Dirk Goetz
userPassword: {SSHA}SmI4N/QECJfMFprv9sMnTD7KZUq46Yw8
givenName: Dirk
mail: dgoetz@localdomain
uid: dgoetz
jpegPhoto:< file:///root/dgoetz.jpg

When I login with the user the avatar is downloaded and the file is created but is not a valid picture.

# file /var/lib/foreman/public/assets/avatars/6e15a0e85405ddd9f25abc3aee0b212ea2ca6bfb.jpg 
/var/lib/foreman/public/assets/avatars/6e15a0e85405ddd9f25abc3aee0b212ea2ca6bfb.jpg: data

If I search the ldap I get:

# dgoetz, users, localdomain
dn: cn=dgoetz,ou=users,dc=localdomain
objectClass: inetOrgPerson
cn: dgoetz
sn: Goetz
description: Dirk Goetz
userPassword:: e1NTSEF9U21JNE4vUUVDSmZNRnBydjlzTW5URDdLWlVxNDZZdzg=
givenName: Dirk
mail: dgoetz@localdomain
uid: dgoetz
jpegPhoto:: /9j/4AAQSkZJRgABAQEBZwFnAAD/4gxYSUNDX1BST0ZJTEUAAQEAAAxITGlubwIQAA
 BtbnRyUkdCIFhZWiAHzgACAAkABgAxAABhY3NwTVNGVAAAAABJRUMgc1JHQgAAAAAAAAAAAAAAAQA
 A9tYAAQAAAADTLUhQICAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
 AAAAABFjcHJ0AAABUAAAADNkZXNjAAABhAAAAGx3dHB0AAAB8AAAABRia3B0AAACBAAAABRyWFlaA
 AACGAAAABRnWFlaAAACLAAAABRiWFlaAAACQAAAABRkbW5kAAACVAAAAHBkbWRkAAACxAAAAIh2dW
 VkAAADTAAAAIZ2aWV3AAAD1AAAACRsdW1pAAAD+AAAABRtZWFzAAAEDAAAACR0ZWNoAAAEMAAAAAx
 yVFJDAAAEPAAACAxnVFJDAAAEPAAACAxiVFJDAAAEPAAACAx0ZXh0AAAAAENvcHlyaWdodCAoYykg
 MTk5OCBIZXdsZXR0LVBhY2thcmQgQ29tcGFueQAAZGVzYwAAAAAAAAASc1JHQiBJRUM2MTk2Ni0yL
 jEAAAAAAAAAAAAAABJzUkdCIElFQzYxOTY2LTIuMQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
 AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAWFlaIAAAAAAAAPNRAAEAAAABFsxYWVogAAAAAAAAAAAAAAA
 AAAAAAFhZWiAAAAAAAABvogAAOPUAAAOQWFlaIAAAAAAAAGKZAAC3hQAAGNpYWVogAAAAAAAAJKAA
 AA+EAAC2z2Rlc2MAAAAAAAAAFklFQyBodHRwOi8vd3d3LmllYy5jaAAAAAAAAAAAAAAAFklFQyBod
 HRwOi8vd3d3LmllYy5jaAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
 AAAABkZXNjAAAAAAAAAC5JRUMgNjE5NjYtMi4xIERlZmF1bHQgUkdCIGNvbG91ciBzcGFjZSAtIHN
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 UXy4AEM8UAAPtzAAEEwsAA1yeAAAAAVhZWiAAAAAAAEwJVgBQAAAAVx/nbWVhcwAAAAAAAAABAAAA
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 shu0R7ZzuKO6070DvzPBY8OXxcvH/8ozzGfOn9DT0wvVQ9d72bfb794r4Gfio+Tj5x/pX+uf7d/wH
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 QAAAAAAAAAAAAAAAAAAAED/2gAIAQIBAT8QB//EAB0QAQEAAgIDAQAAAAAAAAAAAAERACExYRBBUZ
 H/2gAIAQEAAT8QzhIjdTppqx61zgv7AdtHgPsd/j88mGSFiSuhFBbtwLMaiEaB34tg7tFqKdMj7GM
 QmJH+EYqhXKyfriMZJ8dnIbYLCVxzogN3CCivsTgY6xhJuzNA6ZPgw1uKCor7nYY7QAKVPrs5/9k=

And if I copy the base64 string to a file, join the lines and decode it, I get a valid jpeg back.

# cat /tmp/base64 | base64 -d > /tmp/dgoetz.jpg
# file /tmp/dgoetz.jpg 
/tmp/dgoetz.jpg: JPEG image data, JFIF standard 1.01

So something seems to be broken, but looking in the code I have no idea what. When I tried to remove the decoding and output the file in binary I already got some content not maching the base64 string and if output was not written binary I got an empty file. Also removing the to_utf8 for testing showed the same result.