Error Message "Requested revision overlaps with other requested revisions" with branching

[NiklasMM]

I've got a setup with intentional branching (several modules of the core software keep their own line of migrations) and have run into a weird issue, where when upgrading I get the error Requested revision overlaps with other requested revisions.

A minimal example / reproduction path would be this:

• Create base revision A, assign branch-label "base"
• Create revision B which revises A
• Create base revision Z for second branch with label "alt" and add depends_on=["A"]
• Now create an empty DB and stamp it with A and Z.
• Run alembic upgrade heads (the heads are Z for branch alt and B for branch base)

I get the error FAILED: Requested revision Z overlaps with other requested revisions A

I expected it to upgrade A -> B and don't see what is meant by "overlaps" in this case.

Any help would be appreciated!

(I'm running alembic 1.15.2)

[zzzeek]

it's not the problem here, but "base" is a reserved revision name so I'd advise not using that as a name.

the stamp for "A" and "Z" is not how the alembic version table represents this because Z implies A. so you'd just want to "stamp" with Z. it would be nice if "stamp" were smart enough to tell you this but apparently it's not.

$ alembic revision -m "rev a" --rev-id a --branch-label "somebase"
  Generating /home/classic/dev/alembic/foo/versions/a_rev_a.py ...  done
$ alembic revision -m "rev b" --rev-id b
  Generating /home/classic/dev/alembic/foo/versions/b_rev_b.py ...  done
$ alembic revision -m "rev z" --rev-id z --branch-label "alt"  --head base --depends-on a
  Generating /home/classic/dev/alembic/foo/versions/z_rev_z.py ...  done

$ alembic upgrade z
INFO  [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO  [alembic.runtime.migration] Will assume transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> a, rev a
INFO  [alembic.runtime.migration] Running upgrade  -> z, rev z

$ alembic current
INFO  [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO  [alembic.runtime.migration] Will assume transactional DDL.
a
z (head)

$ psql -U scott test -c "select * from alembic_version;"
 version_num 
-------------
 z
(1 row)