Bug#805392: pbuilder: debdelta-upgrade invocation seems incorrect

[Mattia Rizzolo]

control: tags -1 + pending

On Wed, Nov 18, 2015 at 11:33:10AM +0530, Ritesh Raj Sarraf wrote:
> On Tue, 2015-11-17 at 19:52 +0000, Mattia Rizzolo wrote:
> > -    if $CHROOTEXEC hash debdelta-upgrade 2> /dev/null ; then
> > +    if $CHROOTEXEC bash -c "hash debdelta-upgrade 2> /dev/null" ;

> That seems to be the correct root cause.


cool

Though the whole purpose of using `hash` was to avoid spawing yet
another process...  I think would make more sense to switch to it.
Here:
mattia at chase ~ % time /usr/bin/which cat > /dev/null 2>&1
/usr/bin/which cat > /dev/null 2>&1  0.00s user 0.00s system 0% cpu 0.001 total
mattia at chase ~ % time /bin/bash -c "hash cat"
/bin/bash -c "hash cat"  0.00s user 0.00s system 0% cpu 0.004 total

which is quite a difference (clearly spawing a full shell is harder..
even if /bin/which is actually a shell script)
(ok, we're talking about 0.003 seconds, but today I feel like checking
also those :))

So, instead I just committed

-    if $CHROOTEXEC hash debdelta-upgrade 2> /dev/null ; then
+    if $CHROOTEXEC which debdelta-upgrade > /dev/null 2>&1 ; then

which should also make easier to understand to non-bash-savy users.

-- 
regards,
                        Mattia Rizzolo

GPG Key: 66AE 2B4A FCCF 3F52 DA18  4D18 4B04 3FCD B944 4540      .''`.
more about me:  http://mapreri.org                              : :'  :
Launchpad user: https://launchpad.net/~mapreri                  `. `'`
Debian QA page: https://qa.debian.org/developer.php?login=mattia  `-
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