[OSSTEST PATCH] mg-list-all-branches: avoid mistakenly generating `.' in the output

[Ian Jackson <ian.jackson@eu.citrix.com>]

The regex in mg-list-all-branches assumes that the BRANCHES= will
either be a singleton entry separated from the following command by a
hard tab or a single quoted list of space separated entries, however
the xen-unstable-coverity line is singleton separated from the command
by a single space.

We could fix this by using a hard tab, but that ends up aligning
things in an aesthetically displeasing way, and relying on hard tabs
is fragile.

Instead, improve the parsing in mg-list-all-branches: break out a
couple of semantically (as well as syntactically) common regexp
elements out into variables, and then provide two regexps: one which
matches shell "assign default values" substitutions, and the other
which matches the ordinary shell assignments.

We use an empty pair of () in the first regexp to make sure that they
both produce the branch name list in $2.  (It would be possible to use
named capture groups but I'm not sure whether all our perls are recent
enough.)

I have verified that the actual difference in output right now is just
to remove the erroneous `.' entry.

Reported-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
---
 mg-list-all-branches |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/mg-list-all-branches b/mg-list-all-branches
index 87703c7..62d3ff1 100755
--- a/mg-list-all-branches
+++ b/mg-list-all-branches
@@ -7,11 +7,16 @@ use Sort::Versions;
 
 our %branches;
 
+my $branchvar_re = '(?:EXTRA_)?BRANCHES';
+my $branchchr_re = '[-.0-9a-z ]';
+
 foreach my $f (qw(cr-for-branches crontab)) {
     open C, $f or die $!;
     while (<C>) {
-        next unless m/(?:EXTRA_)?BRANCHES[:+]?='?([-.0-9a-z ]+)/;
-        $branches{$_}=1 foreach split /\s+/, $1;
+        next unless
+	    m/\$\{$branchvar_re[:+]?=()($branchchr_re+)\b/ ||
+	    m/$branchvar_re[:+]?=('?)($branchchr_re+?)\1\s/;
+        $branches{$_}=1 foreach split /\s+/, $2;
     }
     close C or die $!;
 }
-- 
1.7.10.4