phabricator: unconditionally pop `test_vcr` to fix debugcallconduit

11592ce6a711 / D8525 accidentally broke debugcallconduit in non-test scenarios
because it stopped popping `test_vcr` from `kwargs` unconditionally, so when
`--test-vcr` isn't set the empty string still gets passed down as the value of
`test_vcr` in `kwargs`.  However unlike all the other commands debugcallconduit
doesn't have an `**opts` argument to receive it, so it aborts because of
invalid arguments.

Differential Revision: https://phab.mercurial-scm.org/D8852

hgext/phabricator.py

@@ -238,8 +238,9 b' def vcrcommand(name, flags, spec, helpca'
 
     def decorate(fn):
         def inner(*args, **kwargs):
-            if kwargs.get('test_vcr'):
-                cassette = pycompat.fsdecode(kwargs.pop('test_vcr'))
+            vcr = kwargs.pop('test_vcr')
+            if vcr:
+                cassette = pycompat.fsdecode(vcr)
                 import hgdemandimport
 
                 with hgdemandimport.deactivated():

tests/test-phabricator.t

@@ -24,16 +24,9 b''
   > EOF
   $ VCR="$TESTDIR/phabricator"
 
-BROKEN: debugcallconduit fails without --test-vcr:
+debugcallconduit doesn't claim invalid arguments without --test-vcr:
   $ echo '{}' | HGRCSKIPREPO= hg debugcallconduit 'conduit.ping'
-  hg debugcallconduit: invalid arguments
-  hg debugcallconduit METHOD
-  
-  call Conduit API
-  
-  options:
-  
-  (use 'hg debugcallconduit -h' to show more help)
+  abort: config phabricator.url is required
   [255]
 
 Error is handled reasonably. We override the phabtoken here so that