Unable to install NO GAPPS version without gapps installed

Hi, I had to reflash my rom due to.. user error and now I can't install ug UnifiedNLP NO GAPPS.

F-droid tells me 'Failed to install due to an unkown error'.
Installing through adb:
```
$ adb install Downloads/NetworkLocation.apk
[100%] /data/local/tmp/NetworkLocation.apk
pkg: /data/local/tmp/NetworkLocation.apk
Failure [INSTALL_FAILED_UPDATE_INCOMPATIBLE]
```

Note: I HAD gapps (they come with the rom) but I removed them.. there might be something left over?

On device:

```
# pm list packages | grep -i goog
package:com.google.android.configupdater
package:com.google.android.webview
package:com.google.android.packageinstaller
package:com.google.android.diskusage

# pm list packages | grep -i locat
package:org.fitchfamily.android.gsmlocation
package:com.android.location.fused
```

Edit: I'm on 6.0.1

Start by reproducing the adb installation failure on Android 6.0.1 and compare the installed packages listed in the report with the NO GAPPS package. Done means identifying the conflicting package or installation condition and documenting a confirmed resolution.

Written by the indexing model from the issue text.