[yocto] local fetcher and devtool don't work well together

[Aaron_Wright at selinc.com]

I have a recipe with:

SRC_URI = "file://a/b/c/d;subdir=src"
S = "${WORKDIR}/src/a/b/c/d"

First off, ${S} must be set to the full path because the basepath uri 
parameter[1] doesn't work. So this doesn't work:

SRC_URI = "file://a/b/c/d;subdir=src;basepath=a/b/c/d"
S = "${WORKDIR}/src"

I wish it would, but that's ok. I can deal with the long ${S} path as it 
compiles and works fine with bitbake. However, it doesn't work with 
devtool:

$ devtool modify -n d ~/mysrc/a/b/c/d
NOTE: Creating workspace layer in <... snip 
...>/yocto/poky/build/workspace
NOTE: Enabling workspace layer in bblayers.conf
Parsing recipes..done.
NOTE: Recipe d now set up to build from ~/mysrc/a/b/c/d/b/c/d

Where is the extra 'b/c/d' coming from in where it will be built from? 
This directory is reflected in the bbappends created the workspace:

FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
FILESPATH_prepend := "~/mysrc/a/b/c/d/b/c/d/oe-local-files:"

inherit externalsrc
# NOTE: We use pn- overrides here to avoid affecting multiple variants in 
the case where the recipe uses BBCLASSEXTEND
EXTERNALSRC_pn-backtrace = "~/mysrc/a/b/c/d/b/c/d"

If I fix the path in the workspace bbappends, it does compile and work 
file.

Is it possible to have a ${S} of "${WORKDIR}/src" in this situation?
How can I get devtool to behave and not duplicate the path?

PS - This also doesn't work with a normal 'devtool modify d'.

[1] - 
https://urldefense.proofpoint.com/v2/url?u=http-3A__www.yoctoproject.org_docs_latest_bitbake-2Duser-2Dmanual_bitbake-2Duser-2Dmanual.html-23bb-2Dthe-2Dunpack&d=DwIBAg&c=zVFQZQ67ypsA9mYKSCqWmQHiVkCCaN-Gb60_N6TVnLk&r=IZ3mUDA8X9CZR4hNctKngDDYs_BhK3qVNLG-nWGbW2E&m=wH_YZj_cv9gBOhJqSKTr4fiuM5UCTphWx9zfY2ceudg&s=2z9LBCu2xDjBhB51eToRNH7-wsLrFY4NPKy4_cwuRI0&e= 
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