doc: build.scm: Handle (current-source-directory) being #f.

Since this seems to be the case when the devel manual is being built on
bayfront.

* doc/build.scm: Use the current working directory as a fallback
if (current-source-directory) is #f, and log the value of root.

Change-Id: Ic43fd05a4a0822d9efb935069850f0a8cadd80aa

1 files changed, 5 insertions, 2 deletions

diff --git a/doc/build.scm b/doc/build.scm
index f7730823186..7238c17a684 100644
--- a/doc/build.scm
+++ b/doc/build.scm
@@ -1475,7 +1475,9 @@ by 'html-identifier-indexes'."
 
 
 (let* ((root (canonicalize-path
-              (string-append (current-source-directory) "/..")))
+              (string-append (or (current-source-directory)
+                                 (string-append (getcwd) "/doc"))
+                             "/..")))
        (commit date (latest-commit+date root))
        (version (or (getenv "GUIX_MANUAL_VERSION")
                     (string-take commit 7)))
@@ -1522,7 +1524,8 @@ by 'html-identifier-indexes'."
     (merge-index-alists guix-split-node-indexes guile-split-node-indexes))
 
   (format (current-error-port)
-          "building manual from work tree around commit ~a, ~a~%"
+          "building manual from work tree (~a) around commit ~a, ~a~%"
+          root
           commit
           (let* ((time (make-time time-utc 0 date))
                  (date (time-utc->date time)))