Versioneer does not work in the Guix build container because:

* VCS information is unavailable
* the build directory does not have the supported "$name-$version" format
* as of 0.21, versioneer has no way to override the discovered values

This patch adds support for extracting version from the
'/tmp/guix-build-foo-0.1.drv-0' style directories created by the daemon.

diff --git a/src/from_parentdir.py b/src/from_parentdir.py
index 69ada9a..e0fac8f 100644
--- a/src/from_parentdir.py
+++ b/src/from_parentdir.py
@@ -15,6 +15,21 @@ def versions_from_parentdir(parentdir_prefix, root, verbose):
             return {"version": dirname[len(parentdir_prefix):],
                     "full-revisionid": None,
                     "dirty": False, "error": None, "date": None}
+        # Guix specific patch: try extracting the version from the build
+        # directory.
+        elif dirname.startswith("guix-build-"):
+            delimiter = dirname.rindex(".drv-")
+            name_and_version = dirname[11:delimiter]
+            if name_and_version.startswith(parentdir_prefix):
+                guix_version = name_and_version[len(parentdir_prefix):]
+            elif name_and_version.startswith("python-{}".format(parentdir_prefix)):
+                guix_version = name_and_version[(7 + len(parentdir_prefix)):]
+            else:
+                break
+            return {"version": guix_version,
+                    "full-revisionid": None,
+                    "dirty": False, "error": None, "date": None}
+
         rootdirs.append(root)
         root = os.path.dirname(root)  # up a level
 
qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=b20c3a4b9a2cc610999935b082cc8f4250962550'>root</a>/<a href='/guix/log/m4?id=b20c3a4b9a2cc610999935b082cc8f4250962550'>m4</a>/<a href='/guix/log/m4/guix.m4?id=b20c3a4b9a2cc610999935b082cc8f4250962550'>guix.m4</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/m4/guix.m4?id=b20c3a4b9a2cc610999935b082cc8f4250962550&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-11-07 18:07:11 +0200'>2023-11-07</span></td><td><a href='/guix/commit/m4/guix.m4?id=220759226e93d76d8d80058f69f9d8b29714bbde'>build: Fix spelling in m4 macros.</a><span class='msg-avail'>...<span class='msg-tooltip'>* m4/guix.m4 (GUIX_CHECK_GUILE_SSH): Fix spelling of parameter.
(GUIX_CHECK_FILE_NAME_LIMITS): Fix spelling of maximum.

Change-Id: I93c80441393622a4bc06daa475eee13874cca527
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2023-03-16 12:37:03 +0100'>2023-03-16</span></td><td><a href='/guix/commit/m4/guix.m4?id=8e3dfb3d6dfc0f19bd9a9f9b163f0f3d7dccc865'>build: Correct guix_system on musl libc distros.</a><span class='msg-avail'>...<span class='msg-tooltip'>* m4/guix.m4 (GUIX_SYSTEM_TYPE): Add linux-musl* case. This prevents
the macro from mis-parsing the host OS, which causes breakage when
building from source.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Antero Mejr</td></tr>