[REG] `--compiler` argument doesn't accept relative path anymore

[Geod24]

DUB version 1.26.0, built on Jun  3 2021

Running on OSX.

% dub --compiler=../../dlang/dmd/generated/osx/release/64/dmd
Running pre-generate commands for vibe-d:tls...
object.Exception@source/dub/dub.d(1418): defaultCompiler specified in a DUB config file cannot use an unqualified relative path:

../../dlang/dmd/generated/osx/release/64/dmd

Use "$DUB_BINARY_PATH/../path/you/want" instead.
----------------
/usr/local/opt/dmd/include/dlang/dmd/core/internal/array/equality.d:237 void dub.dub.Dub.determineDefaultCompiler() [0x1011813f9]
/usr/local/opt/dmd/include/dlang/dmd/core/internal/array/equality.d:237 void dub.dub.Dub.init(dub.internal.vibecompat.inet.path.NativePath) [0x101179059]
/usr/local/opt/dmd/include/dlang/dmd/core/internal/array/equality.d:237 dub.dub.Dub dub.dub.Dub.__ctor(immutable(char)[], dub.packagesuppliers.packagesupplier.PackageSupplier[], dub.dub.SkipPackageSuppliers) [0x101178807]
/usr/local/opt/dmd/include/dlang/dmd/core/internal/array/equality.d:237 dub.dub.Dub dub.commandline.CommandLineHandler.prepareDub() [0x10112d21a]
/usr/local/opt/dmd/include/dlang/dmd/core/internal/array/equality.d:237 int dub.commandline.runDubCommandLine(immutable(char)[][]) [0x10112e0c7]
source/app.d:26 _Dmain [0x10111b62f]
Running pre-generate commands for agora...
object.Exception@source/dub/dub.d(1418): defaultCompiler specified in a DUB config file cannot use an unqualified relative path:

../../dlang/dmd/generated/osx/release/64/dmd

Use "$DUB_BINARY_PATH/../path/you/want" instead.
----------------
/usr/local/opt/dmd/include/dlang/dmd/core/internal/array/equality.d:237 void dub.dub.Dub.determineDefaultCompiler() [0x10b0423f9]
/usr/local/opt/dmd/include/dlang/dmd/core/internal/array/equality.d:237 void dub.dub.Dub.init(dub.internal.vibecompat.inet.path.NativePath) [0x10b03a059]
/usr/local/opt/dmd/include/dlang/dmd/core/internal/array/equality.d:237 dub.dub.Dub dub.dub.Dub.__ctor(immutable(char)[], dub.packagesuppliers.packagesupplier.PackageSupplier[], dub.dub.SkipPackageSuppliers) [0x10b039807]
/usr/local/opt/dmd/include/dlang/dmd/core/internal/array/equality.d:237 dub.dub.Dub dub.commandline.CommandLineHandler.prepareDub() [0x10afee21a]
/usr/local/opt/dmd/include/dlang/dmd/core/internal/array/equality.d:237 int dub.commandline.runDubCommandLine(immutable(char)[][]) [0x10afef0c7]
source/app.d:26 _Dmain [0x10afdc62f]