debugcommands: support wrapping long lines

If a line within a block is indented more than the line that came before,
we automatically concatenate it with the previous line. This allows us to
pretty format data. This will make tests easier to read.

At some point we may just want to evaluate entire blocks as Python
code or something, as even with this change, things aren't perfect, as we
can't e.g. have formatting like:

foo eval:[
    True
]

But this is strictly better than before, where we couldn't wrap long lines.

Differential Revision: https://phab.mercurial-scm.org/D4977

mercurial/debugcommands.py

@@ -2829,6 +2829,7 b' def debugwireargs(ui, repopath, *vals, *'
 def _parsewirelangblocks(fh):
     activeaction = None
     blocklines = []
+    lastindent = 0
 
     for line in fh:
         line = line.rstrip()
@@ -2845,6 +2846,7 b' def _parsewirelangblocks(fh):'
 
             activeaction = line
             blocklines = []
+            lastindent = 0
             continue
 
         # Else we start with an indent.
@@ -2852,7 +2854,14 b' def _parsewirelangblocks(fh):'
         if not activeaction:
             raise error.Abort(_('indented line outside of block'))
 
-        blocklines.append(line)
+        indent = len(line) - len(line.lstrip())
+
+        # If this line is indented more than the last line, concatenate it.
+        if indent > lastindent and blocklines:
+            blocklines[-1] += line.lstrip()
+        else:
+            blocklines.append(line)
+            lastindent = indent
 
     # Flush last block.
     if activeaction: