Using version pinning and virtual packages results in unsatisfiable constraints

When using virtual packages in-conjunction with version pinning results in the package not found. I am trying to install `gdal-dev` which is not in `v3.4` but is in `edge/testing`. If I remove the virtual package, it installs.

Is this possible or bug?

/etc/apk/repositories:

```
http://dl-cdn.alpinelinux.org/alpine/v3.4/main
http://dl-cdn.alpinelinux.org/alpine/v3.4/community
@edge-testing http://dl-cdn.alpinelinux.org/alpine/edge/testing
```

Commands:

```
# apk --no-cache add --virtual .build-deps gdal-dev@edge-testing
fetch http://dl-cdn.alpinelinux.org/alpine/v3.4/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.4/community/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/edge/testing/x86_64/APKINDEX.tar.gz
ERROR: unsatisfiable constraints:
gdal-2.1.0-r1:
masked in: @edge-testing
satisfies: gdal-dev-2.1.0-r1[gdal] gdal-dev-2.1.0-r1[gdal=2.1.0-r1]
gdal-dev-2.1.0-r1:
masked in: @edge-testing
.build-deps-0:
masked in: cache
satisfies: world[.build-deps]
```

Without virtual packages

```
# apk --no-cache add gdal-dev@edge-testing
fetch http://dl-cdn.alpinelinux.org/alpine/v3.4/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.4/community/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/edge/testing/x86_64/APKINDEX.tar.gz
(1/9) Installing libgcc (5.3.0-r0)
(2/9) Installing giflib (5.1.4-r1)
(3/9) Installing libjpeg-turbo (1.4.2-r0)
(4/9) Installing libstdc++ (5.3.0-r0)
(5/9) Installing tiff (4.0.6-r3)
(6/9) Installing gdal@edge-testing (2.1.0-r1)
(7/9) Installing pkgconf (0.9.12-r0)
(8/9) Installing pkgconfig (0.25-r1)
(9/9) Installing gdal-dev@edge-testing (2.1.0-r1)
Executing busybox-1.24.2-r9.trigger
OK: 72 MiB in 41 packages
```