post-applypatch: a bit more commenting

... with no functionality change.

diff --git a/post-applypatch b/post-applypatch
index dbe3e01b928880b7d75055799d3732328b8b4dbe..1aa18f54e5d5bb3fe7011e0241f11d20bbb95043 100755 (executable)
--- a/post-applypatch
+++ b/post-applypatch
@@ -9,11 +9,15 @@ msgnum=$(printf "%0${prec}d" $this) &&
 test -f "$dotest/$msgnum" &&
 message_id=$(sed -ne '
        /^[     ]/{
-               # Append continuation line
+               # Append continuation line to hold space
                H
+               # Swap hold and pattern
                x
+               # Remove the LF, making it a single line
                s/\n//
+               # Swap hold and pattern back
                x
+               # Discard the pattern and go on
                n
        }
        # Hold this new line, and look at what is in the hold space
@@ -35,9 +39,11 @@ message_id=$(sed -ne '
        q
 ' "$dotest/$msgnum") &&
 
-test -n "$message_id" &&
-head=$(git rev-parse --verify HEAD 2>/dev/null) &&
+if     test -n "$message_id" &&
+       head=$(git rev-parse --verify HEAD 2>/dev/null)
+then
+       echo "$head $message_id" >>"$GIT_DIR"/am.log &&
+       GIT_NOTES_REF=refs/notes/amlog \
+               git notes add -f -m "Message-Id: $message_id" "$head"
+fi
 
-echo "$head $message_id" >>"$GIT_DIR"/am.log &&
-GIT_NOTES_REF=refs/notes/amlog \
-       git notes add -f -m "Message-Id: $message_id" "$head"